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 (
    94954, 94955, 95310, 95311, 95317, 95319, 
    95320, 95361, 95362, 95363, 95364, 
    95365, 95366, 95367, 95368, 95369, 
    95370, 95371, 95372, 95373, 95374, 
    95375, 95377, 95392, 95393, 95442, 
    95592, 95593, 95594, 95595
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00085

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "13.52"
    },
    "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": 30,
      "rows_produced_per_join": 30,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "10.52",
        "eval_cost": "3.00",
        "prefix_cost": "13.52",
        "data_read_per_join": "114K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (94954,94955,95310,95311,95317,95319,95320,95361,95362,95363,95364,95365,95366,95367,95368,95369,95370,95371,95372,95373,95374,95375,95377,95392,95393,95442,95592,95593,95594,95595)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
94954
94955
95310
95311
95317
95319
95320
95361
95362
95363
95364
95365
95366
95367
95368
95369
95370
95371
95372
95373
95374
95375
95377
95392
95393
95442
95592
95593
95594
95595