SELECT 
  cscart_product_descriptions.product_id, 
  cscart_product_descriptions.short_description, 
  IF(
    cscart_product_descriptions.short_description = '' 
    OR cscart_product_descriptions.short_description IS NULL, 
    cscart_product_descriptions.full_description, 
    ''
  ) AS full_description, 
  cscart_product_descriptions.unit_name 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    5303, 5360, 5311, 5292, 5341, 5301, 5318, 
    5302, 5342, 5317, 5324, 5298, 5305, 
    5293, 5322, 5343, 5310, 5320, 5299, 
    5319, 5294, 5306, 5325, 5321, 5362, 
    5300, 5345, 5351, 5295, 5323, 5347, 
    5314, 5304, 5357, 5296, 5355, 5361, 
    5327, 5340, 5354
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00218

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "28.33"
    },
    "table": {
      "table_name": "cscart_product_descriptions",
      "access_type": "range",
      "possible_keys": [
        "PRIMARY",
        "product_id"
      ],
      "key": "PRIMARY",
      "used_key_parts": [
        "product_id",
        "lang_code"
      ],
      "key_length": "9",
      "rows_examined_per_scan": 40,
      "rows_produced_per_join": 40,
      "filtered": "100.00",
      "index_condition": "((`softwarepirmam_hewadelivard_cscart_4`.`cscart_product_descriptions`.`product_id` in (5303,5360,5311,5292,5341,5301,5318,5302,5342,5317,5324,5298,5305,5293,5322,5343,5310,5320,5299,5319,5294,5306,5325,5321,5362,5300,5345,5351,5295,5323,5347,5314,5304,5357,5296,5355,5361,5327,5340,5354)) and (`softwarepirmam_hewadelivard_cscart_4`.`cscart_product_descriptions`.`lang_code` = 'en'))",
      "cost_info": {
        "read_cost": "24.33",
        "eval_cost": "4.00",
        "prefix_cost": "28.33",
        "data_read_per_join": "182K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description",
        "unit_name"
      ]
    }
  }
}