SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2137c6f6ff2168ee2aa797a10c46b35c0f835d6b3c456e88fec0f956276f3117' 
  AND token = 'hYPntyuWN+ZN+hXGzoDQ+jA+jB4AAZbgKoK8XFFfjQk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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