SELECT 
  cscart_product_descriptions.product_id, 
  cscart_product_descriptions.meta_keywords, 
  cscart_product_descriptions.meta_description, 
  cscart_product_descriptions.search_words, 
  cscart_product_descriptions.promo_text 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    18672, 18674, 18681, 18723, 20021, 18685, 
    18688, 20050, 19112, 18677, 18678, 
    18680
  ) 
  AND cscart_product_descriptions.lang_code = 'ru'

Query time 0.00187

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "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": 12,
          "filtered": 100,
          "index_condition": "cscart_product_descriptions.product_id in (18672,18674,18681,18723,20021,18685,18688,20050,19112,18677,18678,18680) and cscart_product_descriptions.lang_code = 'ru'"
        }
      }
    ]
  }
}