SELECT 
  f.feature_id, 
  f.purpose, 
  p.product_id, 
  p.parent_product_id, 
  g.id, 
  g.code 
FROM 
  cscart_product_variation_group_features AS f 
  INNER JOIN cscart_product_variation_groups AS g ON f.group_id = g.id 
  INNER JOIN cscart_product_variation_group_products AS p ON f.group_id = p.group_id 
WHERE 
  p.product_id IN (
    18, 16, 4, 5, 349, 350, 428, 23, 24, 1, 450, 
    451, 452, 453, 454, 455, 22, 25, 6, 8, 
    14, 9, 10, 19, 21
  )

Query time 0.00084

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "117.26"
    },
    "nested_loop": [
      {
        "table": {
          "table_name": "p",
          "access_type": "ALL",
          "possible_keys": [
            "PRIMARY",
            "idx_group_id"
          ],
          "rows_examined_per_scan": 61,
          "rows_produced_per_join": 24,
          "filtered": "40.98",
          "cost_info": {
            "read_cost": "9.39",
            "eval_cost": "5.00",
            "prefix_cost": "14.39",
            "data_read_per_join": "399"
          },
          "used_columns": [
            "product_id",
            "parent_product_id",
            "group_id"
          ],
          "attached_condition": "(`pankajecarter_systemfour`.`p`.`product_id` in (18,16,4,5,349,350,428,23,24,1,450,451,452,453,454,455,22,25,6,8,14,9,10,19,21))"
        }
      },
      {
        "table": {
          "table_name": "g",
          "access_type": "eq_ref",
          "possible_keys": [
            "PRIMARY"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "id"
          ],
          "key_length": "3",
          "ref": [
            "pankajecarter_systemfour.p.group_id"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 24,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "25.00",
            "eval_cost": "5.00",
            "prefix_cost": "44.39",
            "data_read_per_join": "9K"
          },
          "used_columns": [
            "id",
            "code"
          ]
        }
      },
      {
        "table": {
          "table_name": "f",
          "access_type": "ref",
          "possible_keys": [
            "idx_group_id"
          ],
          "key": "idx_group_id",
          "used_key_parts": [
            "group_id"
          ],
          "key_length": "3",
          "ref": [
            "pankajecarter_systemfour.p.group_id"
          ],
          "rows_examined_per_scan": 3,
          "rows_produced_per_join": 89,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "55.00",
            "eval_cost": "17.87",
            "prefix_cost": "117.27",
            "data_read_per_join": "9K"
          },
          "used_columns": [
            "feature_id",
            "purpose",
            "group_id"
          ]
        }
      }
    ]
  }
}