SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '42e68f99974a51d5581455d004847550480f95b5f162164b3893517496f1a55e' 
  AND token = '9pqyH6Lqtw32xvpxKuQcp8hHNryx0xz1naCRtmxgMQU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}