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 (
    85513, 85317, 85318, 85414, 85415, 85465, 
    85466, 85516, 85517, 86471, 86472, 
    86747, 86748, 85838, 85839, 82852, 
    82853, 82925, 82926, 82998, 82999, 
    83514, 83515, 83522, 83523, 85844, 
    85845, 86192, 86215, 86524
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00070

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 (85513,85317,85318,85414,85415,85465,85466,85516,85517,86471,86472,86747,86748,85838,85839,82852,82853,82925,82926,82998,82999,83514,83515,83522,83523,85844,85845,86192,86215,86524)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}