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 (
    1557, 1556, 1555, 1554, 1553, 1551, 1549, 
    1546, 1545, 1544, 1543, 1542, 1541, 
    1540, 1539, 1538, 1537, 1512, 1534, 
    1533, 1515, 1532, 1531, 1530, 1529, 
    1528, 1527, 1526, 1508, 1525, 1524, 
    1509, 1523, 1522, 1521, 1520, 1519, 
    1518, 1517, 1516, 1277, 1494, 1507, 
    1499, 1505, 1504, 1503, 1502
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00156

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 (1557,1556,1555,1554,1553,1551,1549,1546,1545,1544,1543,1542,1541,1540,1539,1538,1537,1512,1534,1533,1515,1532,1531,1530,1529,1528,1527,1526,1508,1525,1524,1509,1523,1522,1521,1520,1519,1518,1517,1516,1277,1494,1507,1499,1505,1504,1503,1502) and cscart_product_descriptions.lang_code = 'en'"
    }
  }
}

Result

product_id short_description full_description meta_keywords meta_description search_words promo_text unit_name
1277
1494
1499
1502
1503
1504
1505
1507
1508
1509
1512
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1549
1551
1553
1554
1555
1556
1557