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 (
    263981, 264973, 264102, 366828, 371861, 
    366833, 366771, 371878, 366815, 371873, 
    366690, 371884, 371890, 371868, 366760, 
    371898, 371895, 366821, 371902
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00137

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "26.64"
    },
    "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": 19,
      "rows_produced_per_join": 19,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "22.84",
        "eval_cost": "3.80",
        "prefix_cost": "26.64",
        "data_read_per_join": "129K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`webmarco`.`cscart_product_descriptions`.`product_id` in (263981,264973,264102,366828,371861,366833,366771,371878,366815,371873,366690,371884,371890,371868,366760,371898,371895,366821,371902)) and (`webmarco`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}