SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8320cb44d25897182f31c4f18e630a1e49e6cd6838f8477306ff80d0e7cf5aba' 
  AND token = '5i8EUYKWOyKoEiF0P8XVRcGON8AsYa0CCOYGuFcr6UI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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