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 (
    87823, 87874, 87779, 87783, 87793, 87799, 
    87880, 87873, 90317, 90319, 90320, 
    88087, 88797, 87960, 87778, 87782, 
    87791, 87797, 87760, 88701, 88748, 
    88596, 88030, 88086, 87759, 88019, 
    87992, 88001, 88005, 87939
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00082

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 (87823,87874,87779,87783,87793,87799,87880,87873,90317,90319,90320,88087,88797,87960,87778,87782,87791,87797,87760,88701,88748,88596,88030,88086,87759,88019,87992,88001,88005,87939)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}