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 (
    1692, 1695, 1694, 1693, 1691, 1690, 1688, 
    1678, 1680, 1681, 1664, 1687, 1685, 
    1684, 1677, 1644, 1674, 1673, 1672, 
    1671, 1670, 1669, 1668, 1667
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00106

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 (1692,1695,1694,1693,1691,1690,1688,1678,1680,1681,1664,1687,1685,1684,1677,1644,1674,1673,1672,1671,1670,1669,1668,1667) and cscart_product_descriptions.lang_code = 'en'"
    }
  }
}

Result

product_id short_description full_description meta_keywords meta_description search_words promo_text unit_name
1644
1664
1667
1668
1669
1670
1671
1672
1673
1674
1677
1678
1680
1681
1684
1685
1687
1688
1690
1691
1692
1693
1694
1695