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 (
    2771, 4992, 5661, 2774, 2455, 5207, 5737, 
    6385, 5186, 5008, 1517, 4991, 5272, 
    2438, 5276, 8498, 5660, 7624, 8484, 
    8497, 5285, 5346, 2812, 5728, 7608, 
    5879, 2250, 8485, 1538, 5265, 8488, 
    8486, 8492, 2899, 5288, 8487, 5523, 
    7614, 5666, 6823
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00106

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 (2771,4992,5661,2774,2455,5207,5737,6385,5186,5008,1517,4991,5272,2438,5276,8498,5660,7624,8484,8497,5285,5346,2812,5728,7608,5879,2250,8485,1538,5265,8488,8486,8492,2899,5288,8487,5523,7614,5666,6823)) 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"
      ]
    }
  }
}