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 (
    86214, 86522, 86523, 86798, 86799, 90008, 
    84667, 85821, 84347, 84659, 84660, 
    88689, 88736, 86489, 86765, 86188, 
    86211, 86520, 86796, 82603, 82605, 
    85079, 85165, 85211, 85257, 89242, 
    83071, 83072, 83624, 83625
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00096

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 (86214,86522,86523,86798,86799,90008,84667,85821,84347,84659,84660,88689,88736,86489,86765,86188,86211,86520,86796,82603,82605,85079,85165,85211,85257,89242,83071,83072,83624,83625)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}