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 (
    180, 18, 16, 9, 10, 24, 189, 190, 245, 239, 
    238, 23, 22, 25, 19, 65, 64, 62, 134, 135, 
    74, 73, 71, 75, 72, 255, 21, 70, 76, 30, 
    246, 29
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.01581

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_product_descriptions",
          "access_type": "range",
          "possible_keys": ["PRIMARY", "product_id"],
          "key": "PRIMARY",
          "key_length": "9",
          "used_key_parts": ["product_id", "lang_code"],
          "rows": 32,
          "filtered": 100,
          "index_condition": "cscart_product_descriptions.product_id in (180,18,16,9,10,24,189,190,245,239,238,23,22,25,19,65,64,62,134,135,74,73,71,75,72,255,21,70,76,30,246,29) and cscart_product_descriptions.lang_code = 'en'"
        }
      }
    ]
  }
}