SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '4f419798b8857daeb159ffee14d6089c980992353f95694a23ca72723d07db1b' 
  AND token = '7JRw1V/f44924q+a66xEJW4i9kkvGSZYADKXfEyU41w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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