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 (
    96369, 96370, 96371, 96372, 96373, 96374, 
    96375, 96376, 96377, 96378, 96379, 
    96380, 96381, 96382, 96392, 96393, 
    96401, 96402, 96403, 96404, 96405, 
    96406, 96407, 96408, 96411, 96412, 
    96413, 96414, 96415, 96416, 96417, 
    96418, 96419, 96420, 96421, 96422, 
    96423, 96424, 96425, 96426, 96427, 
    96428, 96430, 96431, 96434, 96435, 
    96436, 96437
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00102

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "21.62"
    },
    "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": "16.82",
        "eval_cost": "4.80",
        "prefix_cost": "21.62",
        "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 (96369,96370,96371,96372,96373,96374,96375,96376,96377,96378,96379,96380,96381,96382,96392,96393,96401,96402,96403,96404,96405,96406,96407,96408,96411,96412,96413,96414,96415,96416,96417,96418,96419,96420,96421,96422,96423,96424,96425,96426,96427,96428,96430,96431,96434,96435,96436,96437)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
96369
96370
96371
96372
96373
96374
96375
96376
96377
96378
96379
96380
96381
96382
96392
96393
96401
96402
96403
96404
96405
96406
96407
96408
96411
96412
96413
96414
96415
96416
96417
96418
96419
96420
96421
96422
96423
96424
96425
96426
96427
96428
96430
96431
96434
96435
96436
96437