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 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    99891, 99892, 99893, 99894, 99895, 99896, 
    99897, 99898, 99899, 99900, 99901, 
    99902, 99903, 99904, 99905, 99906, 
    99907, 99908, 99909, 99910, 99911, 
    99912, 99913, 99914, 99915, 99916, 
    99917, 99918, 99919, 99920, 99921, 
    99922, 99923, 99924, 99925, 99926, 
    99927, 99928, 99929, 99930, 99931, 
    99932, 99933, 99934, 99935, 99936, 
    99937, 99938
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00060

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "21.63"
    },
    "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": 48,
      "rows_produced_per_join": 48,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "16.83",
        "eval_cost": "4.80",
        "prefix_cost": "21.63",
        "data_read_per_join": "183K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (99891,99892,99893,99894,99895,99896,99897,99898,99899,99900,99901,99902,99903,99904,99905,99906,99907,99908,99909,99910,99911,99912,99913,99914,99915,99916,99917,99918,99919,99920,99921,99922,99923,99924,99925,99926,99927,99928,99929,99930,99931,99932,99933,99934,99935,99936,99937,99938)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}