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 (
    97928, 97929, 97930, 97931, 97932, 97933, 
    97934, 97935, 97936, 97937, 97938, 
    97939, 97940, 97941, 97942, 97943, 
    97944, 97945, 97946, 97947, 97948, 
    97949, 97950, 97951, 97952, 97960, 
    97961, 97962, 97963, 97964
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00076

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 (97928,97929,97930,97931,97932,97933,97934,97935,97936,97937,97938,97939,97940,97941,97942,97943,97944,97945,97946,97947,97948,97949,97950,97951,97952,97960,97961,97962,97963,97964)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
97928
97929
97930
97931
97932
97933
97934
97935
97936
97937
97938
97939
97940
97941
97942
97943
97944
97945
97946
97947
97948
97949
97950
97951
97952
97960
97961
97962
97963
97964