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 (
    1623, 1614, 1604, 1801, 1802, 1724, 1727, 
    1726, 1599, 1725, 1600, 1872, 1603, 
    1560, 1513, 1550, 1548, 1547, 1763, 
    1764, 1506, 1735, 1602, 1601, 1692, 
    1696, 1682, 1743, 1556, 1555, 1554, 
    1553
  ) 
  AND cscart_product_descriptions.lang_code = 'ja'

Query time 0.00120

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": 32,
      "filtered": 100,
      "index_condition": "cscart_product_descriptions.product_id in (1623,1614,1604,1801,1802,1724,1727,1726,1599,1725,1600,1872,1603,1560,1513,1550,1548,1547,1763,1764,1506,1735,1602,1601,1692,1696,1682,1743,1556,1555,1554,1553) and cscart_product_descriptions.lang_code = 'ja'"
    }
  }
}

Result

product_id short_description full_description meta_keywords meta_description search_words promo_text unit_name
1506
1513
1547
1548
1550
1553
1554
1555
1556
1560
1599
1600
1601
1602
1603
1604
1614
1623
1682
1692
1696
1724
1725
1726
1727
1735
1743
1763
1764
1801
1802
1872