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.meta_keywords, 
  cscart_product_descriptions.meta_description, 
  cscart_product_descriptions.search_words, 
  cscart_product_descriptions.promo_text, 
  cscart_product_descriptions.unit_name 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    1603, 1602, 1601, 1600, 1599, 1598, 1597, 
    1565, 1586, 1577, 1595, 1594, 1593, 
    1591, 1590, 1589, 1588, 1587, 1579, 
    1585, 1584, 1514, 1583, 1582
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00097

JSON explain

{
  "query_block": {
    "select_id": 1,
    "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": 24,
      "filtered": 100,
      "index_condition": "cscart_product_descriptions.product_id in (1603,1602,1601,1600,1599,1598,1597,1565,1586,1577,1595,1594,1593,1591,1590,1589,1588,1587,1579,1585,1584,1514,1583,1582) and cscart_product_descriptions.lang_code = 'en'"
    }
  }
}

Result

product_id short_description full_description meta_keywords meta_description search_words promo_text unit_name
1514
1565
1577
1579
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1593
1594
1595
1597
1598
1599
1600
1601
1602
1603