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 (
    1336, 1837, 1820, 1304, 1738, 1893, 1895, 
    1894, 1641, 1500, 1317, 1670, 1658, 
    1558, 1644, 1262, 1552, 1398, 1595, 
    1576, 1870, 1691, 1776, 1785, 1633, 
    1563, 1564, 1667, 1786, 1945, 1910, 
    1787, 1308, 1642, 1772, 1736, 1277, 
    1672, 1325, 1665, 1778, 1775, 1671, 
    1649, 1909, 1948, 1612, 1267
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00151

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": 48,
      "filtered": 100,
      "index_condition": "cscart_product_descriptions.product_id in (1336,1837,1820,1304,1738,1893,1895,1894,1641,1500,1317,1670,1658,1558,1644,1262,1552,1398,1595,1576,1870,1691,1776,1785,1633,1563,1564,1667,1786,1945,1910,1787,1308,1642,1772,1736,1277,1672,1325,1665,1778,1775,1671,1649,1909,1948,1612,1267) and cscart_product_descriptions.lang_code = 'en'"
    }
  }
}

Result

product_id short_description full_description meta_keywords meta_description search_words promo_text unit_name
1262
1267
1277
1304
1308
1317
1325
1336
1398
1500
1552
1558
1563
1564
1576
1595
1612
1633
1641
1642
1644
1649
1658
1665
1667
1670
1671
1672
1691
1736
1738
1772
1775
1776
1778
1785
1786
1787
1820
1837
1870
1893
1894
1895
1909
1910
1945
1948