SELECT 
  cscart_product_descriptions.product_id, 
  cscart_product_descriptions.unit_name 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (65, 63, 62, 66) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00089

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "51.60"
    },
    "table": {
      "table_name": "cscart_product_descriptions",
      "access_type": "ALL",
      "rows_examined_per_scan": 248,
      "rows_produced_per_join": 9,
      "filtered": "4.00",
      "cost_info": {
        "read_cost": "50.60",
        "eval_cost": "0.99",
        "prefix_cost": "51.60",
        "data_read_per_join": "45K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "unit_name"
      ],
      "attached_condition": "((`mobikul_delivery_boy_livedemo`.`cscart_product_descriptions`.`product_id` in (65,63,62,66)) and (`mobikul_delivery_boy_livedemo`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}