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 (
    1273, 1134, 607, 1092, 584, 1132, 446, 
    492, 461, 399, 649, 1129, 930, 931, 977, 
    929, 1020, 928, 749, 40, 416, 405, 427, 
    444
  ) 
  AND cscart_product_descriptions.lang_code = 'ja'

Query time 0.00101

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 (1273,1134,607,1092,584,1132,446,492,461,399,649,1129,930,931,977,929,1020,928,749,40,416,405,427,444) and cscart_product_descriptions.lang_code = 'ja'"
    }
  }
}

Result

product_id short_description full_description meta_keywords meta_description search_words promo_text unit_name
40
399
405
416
427
444
446
461
492
584
607
649
749
928
929
930
931
977
1020
1092
1129
1132
1134
1273