SELECT 
  cscart_products_categories.product_id, 
  GROUP_CONCAT(
    IF(
      cscart_products_categories.link_type = "M", 
      CONCAT(
        cscart_products_categories.category_id, 
        "M"
      ), 
      cscart_products_categories.category_id
    )
  ) AS category_ids, 
  product_position_source.position AS position 
FROM 
  cscart_products_categories 
  INNER JOIN cscart_categories ON cscart_categories.category_id = cscart_products_categories.category_id 
  AND cscart_categories.storefront_id IN (0, 1) 
  AND (
    cscart_categories.usergroup_ids = '' 
    OR FIND_IN_SET(
      0, cscart_categories.usergroup_ids
    ) 
    OR FIND_IN_SET(
      1, cscart_categories.usergroup_ids
    )
  ) 
  AND cscart_categories.status IN ('A', 'H') 
  LEFT JOIN cscart_products_categories AS product_position_source ON cscart_products_categories.product_id = product_position_source.product_id 
  AND product_position_source.category_id = 234 
WHERE 
  cscart_products_categories.product_id IN (
    245, 238, 239, 74, 73, 71, 75, 72, 70, 76, 
    67, 86, 106, 105, 101, 69, 125, 120, 117, 
    113, 331, 335, 339, 341, 355, 356, 357, 
    358, 359, 360, 361, 362, 363, 364, 365, 
    366, 367, 368, 369, 370, 379, 380, 381, 
    382, 383, 384, 385, 386, 387, 388, 389, 
    390, 391, 392, 393, 394, 395, 396, 397, 
    398, 399, 400, 401, 402, 403, 404, 405, 
    406, 407, 408, 409, 410, 411, 412, 413, 
    414, 415, 416, 417, 418, 419, 420, 421, 
    422, 423, 424, 425, 426, 68
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00132

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "41.25"
    },
    "grouping_operation": {
      "using_temporary_table": true,
      "using_filesort": true,
      "cost_info": {
        "sort_cost": "2.59"
      },
      "nested_loop": [
        {
          "table": {
            "table_name": "cscart_categories",
            "access_type": "ALL",
            "possible_keys": [
              "PRIMARY",
              "c_status",
              "p_category_id"
            ],
            "rows_examined_per_scan": 84,
            "rows_produced_per_join": 3,
            "filtered": "4.00",
            "cost_info": {
              "read_cost": "19.53",
              "eval_cost": "0.67",
              "prefix_cost": "20.20",
              "data_read_per_join": "8K"
            },
            "used_columns": [
              "category_id",
              "storefront_id",
              "usergroup_ids",
              "status"
            ],
            "attached_condition": "((`pankajecarter_systemfour`.`cscart_categories`.`storefront_id` in (0,1)) and ((`pankajecarter_systemfour`.`cscart_categories`.`usergroup_ids` = '') or find_in_set(0,`pankajecarter_systemfour`.`cscart_categories`.`usergroup_ids`) or find_in_set(1,`pankajecarter_systemfour`.`cscart_categories`.`usergroup_ids`)) and (`pankajecarter_systemfour`.`cscart_categories`.`status` in ('A','H')))"
          }
        },
        {
          "table": {
            "table_name": "cscart_products_categories",
            "access_type": "ref",
            "possible_keys": [
              "PRIMARY",
              "pt"
            ],
            "key": "PRIMARY",
            "used_key_parts": [
              "category_id"
            ],
            "key_length": "3",
            "ref": [
              "pankajecarter_systemfour.cscart_categories.category_id"
            ],
            "rows_examined_per_scan": 3,
            "rows_produced_per_join": 2,
            "filtered": "25.69",
            "index_condition": "(`pankajecarter_systemfour`.`cscart_products_categories`.`product_id` in (245,238,239,74,73,71,75,72,70,76,67,86,106,105,101,69,125,120,117,113,331,335,339,341,355,356,357,358,359,360,361,362,363,364,365,366,367,368,369,370,379,380,381,382,383,384,385,386,387,388,389,390,391,392,393,394,395,396,397,398,399,400,401,402,403,404,405,406,407,408,409,410,411,412,413,414,415,416,417,418,419,420,421,422,423,424,425,426,68))",
            "cost_info": {
              "read_cost": "13.34",
              "eval_cost": "0.52",
              "prefix_cost": "35.55",
              "data_read_per_join": "41"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "link_type"
            ]
          }
        },
        {
          "table": {
            "table_name": "product_position_source",
            "access_type": "eq_ref",
            "possible_keys": [
              "PRIMARY",
              "pt"
            ],
            "key": "PRIMARY",
            "used_key_parts": [
              "category_id",
              "product_id"
            ],
            "key_length": "6",
            "ref": [
              "const",
              "pankajecarter_systemfour.cscart_products_categories.product_id"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 2,
            "filtered": "100.00",
            "cost_info": {
              "read_cost": "2.59",
              "eval_cost": "0.52",
              "prefix_cost": "38.66",
              "data_read_per_join": "41"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "position"
            ]
          }
        }
      ]
    }
  }
}