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, 
  cscart_product_descriptions.unit_name 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    35, 47, 81, 107, 109, 91, 92, 161, 188, 
    202, 203, 34, 31, 38, 80, 165, 166, 86, 
    106, 105, 247, 101, 33, 32, 163, 244, 
    212, 155, 102, 12, 564, 570
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00123

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "44.91"
    },
    "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": 32,
      "rows_produced_per_join": 32,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "38.51",
        "eval_cost": "6.40",
        "prefix_cost": "44.91",
        "data_read_per_join": "146K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description",
        "unit_name"
      ],
      "attached_condition": "((`twebezli_Commercemodalpopup`.`cscart_product_descriptions`.`product_id` in (35,47,81,107,109,91,92,161,188,202,203,34,31,38,80,165,166,86,106,105,247,101,33,32,163,244,212,155,102,12,564,570)) and (`twebezli_Commercemodalpopup`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}