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 (
    357, 354, 103, 155, 763, 15, 1223, 304, 
    1130, 337, 1135, 366, 1137, 1138, 1271, 
    1192, 1173, 142, 143, 369, 1313, 20, 
    16, 144, 145, 97, 52, 291, 76, 313, 1213, 
    1348, 1349, 801, 604
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00127

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": 35,
      "filtered": 100,
      "index_condition": "cscart_product_descriptions.product_id in (357,354,103,155,763,15,1223,304,1130,337,1135,366,1137,1138,1271,1192,1173,142,143,369,1313,20,16,144,145,97,52,291,76,313,1213,1348,1349,801,604) and cscart_product_descriptions.lang_code = 'en'"
    }
  }
}

Result

product_id short_description full_description meta_keywords meta_description search_words promo_text unit_name
15
16
20
52
76
97
103
142
143
144
145
155
291
304
313
337
354
357
366
369
604
763
801
1130
1135
1137
1138
1173
1192
1213
1223
1271
1313
1348
1349