SELECT 
  cscart_product_descriptions.product_id, 
  cscart_product_descriptions.unit_name 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    23759, 23760, 23761, 23762, 23763, 23764, 
    23765, 23766, 23767, 23768, 23769, 
    23770, 23771, 23772, 8323, 8325
  ) 
  AND cscart_product_descriptions.lang_code = 'ru'

Query time 0.00108

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_product_descriptions",
      "access_type": "range",
      "possible_keys": ["PRIMARY", "product_id", "idx_product_lang"],
      "key": "PRIMARY",
      "key_length": "9",
      "used_key_parts": ["product_id", "lang_code"],
      "rows": 16,
      "filtered": 100,
      "index_condition": "cscart_product_descriptions.product_id in (23759,23760,23761,23762,23763,23764,23765,23766,23767,23768,23769,23770,23771,23772,8323,8325) and cscart_product_descriptions.lang_code = 'ru'"
    }
  }
}