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 (
    101132, 101133, 101514, 101515, 101516, 
    101517, 101523, 101524, 101525, 101526, 
    101532, 101533, 101534, 101535, 101552, 
    101553, 101554, 101555, 101561, 101562, 
    101563, 101564, 101570, 101571, 101572, 
    101573, 101635, 101636, 101639, 101640
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00063

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 (101132,101133,101514,101515,101516,101517,101523,101524,101525,101526,101532,101533,101534,101535,101552,101553,101554,101555,101561,101562,101563,101564,101570,101571,101572,101573,101635,101636,101639,101640)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}