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 (
    85018, 85024, 85030, 85036, 85017, 85023, 
    85029, 85035, 89215, 89228, 89241, 
    88176, 88224, 88244, 88248, 88772, 
    88531, 87461, 88501, 85729, 85746, 
    85756, 85766, 85736, 88771, 88174, 
    88222, 88243, 88247, 89454
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00047

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 (85018,85024,85030,85036,85017,85023,85029,85035,89215,89228,89241,88176,88224,88244,88248,88772,88531,87461,88501,85729,85746,85756,85766,85736,88771,88174,88222,88243,88247,89454)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}