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 (
    83347, 88245, 82591, 83354, 89781, 89828, 
    89829, 89880, 89881, 89952, 89953, 
    91518, 91519, 84882, 84897, 82574, 
    82575, 83161, 83162, 84672, 85015, 
    85021, 85027, 85033, 85331, 85332, 
    86488, 86764, 91141, 91142
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00084

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 (83347,88245,82591,83354,89781,89828,89829,89880,89881,89952,89953,91518,91519,84882,84897,82574,82575,83161,83162,84672,85015,85021,85027,85033,85331,85332,86488,86764,91141,91142)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}