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 (
    1867, 1721, 1145, 1891, 1202, 247, 296, 
    1218, 1765, 820, 1816, 1651, 1661, 255, 
    65, 1959, 1011, 1685, 1207, 1210, 1203, 
    1389, 1188, 1190
  ) 
  AND cscart_product_descriptions.lang_code = 'ja'

Query time 0.00118

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 (1867,1721,1145,1891,1202,247,296,1218,1765,820,1816,1651,1661,255,65,1959,1011,1685,1207,1210,1203,1389,1188,1190) and cscart_product_descriptions.lang_code = 'ja'"
    }
  }
}

Result

product_id short_description full_description meta_keywords meta_description search_words promo_text unit_name
65
247
255
296
820
1011
1145
1188
1190
1202
1203
1207
1210
1218
1389
1651
1661
1685
1721
1765
1816
1867
1891
1959