SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6d1479cc46ac127b6042b298a60af5d1d674cce704b528c63840bb98a89cfb4' 
  AND token = '3J1mgqU01rLzKf+EBAkn/CaPHvJUr8Wh8AGSH/jtMJA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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