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, 
  cscart_product_descriptions.unit_name 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    10455, 10456, 10453, 10452, 10451, 10450, 
    10449, 10448, 10447, 12691, 12692, 
    12693, 12694, 12695, 12696, 12697, 
    12698, 12699
  ) 
  AND cscart_product_descriptions.lang_code = 'ru'

Query time 0.00074

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": 18,
      "filtered": 100,
      "index_condition": "cscart_product_descriptions.product_id in (10455,10456,10453,10452,10451,10450,10449,10448,10447,12691,12692,12693,12694,12695,12696,12697,12698,12699) and cscart_product_descriptions.lang_code = 'ru'"
    }
  }
}