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 (
    5022, 5006, 3927, 4781, 3335, 4961, 5009, 
    3336, 5208, 3954, 3509, 3934, 3961, 
    4006, 5467, 5554, 3958, 5013, 3933, 
    5370, 8789, 3484, 5566, 4824, 4989, 
    5377, 3477, 4821, 5369, 4660, 5188, 
    5567, 4238, 3468, 4005, 4010, 5477, 
    4292, 5866, 5374
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00111

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 (5022,5006,3927,4781,3335,4961,5009,3336,5208,3954,3509,3934,3961,4006,5467,5554,3958,5013,3933,5370,8789,3484,5566,4824,4989,5377,3477,4821,5369,4660,5188,5567,4238,3468,4005,4010,5477,4292,5866,5374)) 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"
      ]
    }
  }
}