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 (
    98977, 98978, 98979, 98980, 98981, 98982, 
    98983, 98984, 98985, 98986, 98987, 
    98988, 98989, 98990, 98991, 98992, 
    98993, 98994, 98995, 98996, 98997, 
    98998, 98999, 99000, 99001, 99002, 
    99003, 99004, 99005, 99006, 99007, 
    99008, 99009, 99010, 99011, 99066, 
    99333, 99334, 99335, 99336, 99337, 
    99338, 99339, 99340, 99341, 99342, 
    99343, 99491
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00110

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 (98977,98978,98979,98980,98981,98982,98983,98984,98985,98986,98987,98988,98989,98990,98991,98992,98993,98994,98995,98996,98997,98998,98999,99000,99001,99002,99003,99004,99005,99006,99007,99008,99009,99010,99011,99066,99333,99334,99335,99336,99337,99338,99339,99340,99341,99342,99343,99491)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
98977
98978
98979
98980
98981
98982
98983
98984
98985
98986
98987
98988
98989
98990
98991
98992
98993
98994
98995
98996
98997
98998
98999
99000
99001
99002
99003
99004
99005
99006
99007
99008
99009
99010
99011
99066
99333
99334
99335
99336
99337
99338
99339
99340
99341
99342
99343
99491