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 (
    699, 711, 703, 710, 706, 1760, 1844, 1689, 
    1754, 1755, 1840, 1756, 1753, 1472, 
    1145, 1202, 247, 296, 1765, 820, 1816, 
    1766, 1219, 1220
  ) 
  AND cscart_product_descriptions.lang_code = 'ja'

Query time 0.00103

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 (699,711,703,710,706,1760,1844,1689,1754,1755,1840,1756,1753,1472,1145,1202,247,296,1765,820,1816,1766,1219,1220) and cscart_product_descriptions.lang_code = 'ja'"
    }
  }
}

Result

product_id short_description full_description meta_keywords meta_description search_words promo_text unit_name
247
296
699
703
706
710
711
820
1145
1202
1219
1220
1472
1689
1753
1754
1755
1756
1760
1765
1766
1816
1840
1844