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 (
    96354, 96355, 96356, 96357, 96358, 96359, 
    96360, 96361, 96362, 96363, 96364, 
    96365, 96366, 96367, 96368, 96369, 
    96370, 96371, 96372, 96373, 96374, 
    96375, 96376, 96377, 96378, 96379, 
    96380, 96381, 96382, 96383, 96384, 
    96385, 96386, 96387, 96388, 96389, 
    96390, 96391, 96392, 96393, 96394, 
    96395, 96396, 96397, 96398, 96399, 
    96400, 96401
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00101

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 (96354,96355,96356,96357,96358,96359,96360,96361,96362,96363,96364,96365,96366,96367,96368,96369,96370,96371,96372,96373,96374,96375,96376,96377,96378,96379,96380,96381,96382,96383,96384,96385,96386,96387,96388,96389,96390,96391,96392,96393,96394,96395,96396,96397,96398,96399,96400,96401)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
96354
96355
96356
96357
96358
96359
96360
96361
96362
96363
96364
96365
96366
96367
96368
96369
96370
96371
96372
96373
96374
96375
96376
96377
96378
96379
96380
96381
96382
96383
96384
96385
96386
96387
96388
96389
96390
96391
96392
96393
96394
96395
96396
96397
96398
96399
96400
96401