SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    329, 330, 331, 333, 334, 335, 337, 338, 
    339, 341, 342, 343, 371, 372, 373, 374, 
    375, 376, 377, 378
  )

Query time 0.00068

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "48.01"
    },
    "table": {
      "table_name": "cscart_products",
      "access_type": "range",
      "possible_keys": [
        "PRIMARY"
      ],
      "key": "PRIMARY",
      "used_key_parts": [
        "product_id"
      ],
      "key_length": "3",
      "rows_examined_per_scan": 20,
      "rows_produced_per_join": 20,
      "filtered": "100.00",
      "index_condition": "(`pankajecarter_systemfour`.`cscart_products`.`product_id` in (329,330,331,333,334,335,337,338,339,341,342,343,371,372,373,374,375,376,377,378))",
      "cost_info": {
        "read_cost": "44.01",
        "eval_cost": "4.00",
        "prefix_cost": "48.01",
        "data_read_per_join": "88K"
      },
      "used_columns": [
        "product_id",
        "product_code",
        "product_type",
        "status",
        "company_id",
        "list_price",
        "amount",
        "weight",
        "length",
        "width",
        "height",
        "shipping_freight",
        "low_avail_limit",
        "timestamp",
        "updated_timestamp",
        "usergroup_ids",
        "is_edp",
        "edp_shipping",
        "unlimited_download",
        "tracking",
        "free_shipping",
        "zero_price_action",
        "is_pbp",
        "is_op",
        "is_oper",
        "is_returnable",
        "return_period",
        "avail_since",
        "out_of_stock_actions",
        "localization",
        "min_qty",
        "max_qty",
        "qty_step",
        "list_qty_count",
        "tax_ids",
        "age_verification",
        "age_limit",
        "options_type",
        "exceptions_type",
        "details_layout",
        "shipping_params",
        "show_videos_before_images",
        "autoplay_videos",
        "facebook_obj_type",
        "parent_product_id",
        "buy_now_url",
        "units_in_product",
        "show_price_per_x_units"
      ]
    }
  }
}