SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '30fab143a5a61b629a34d81a13525ad8973f0541d95881763a9ac350cd11bb68' 
  AND token = 'QWdg0H8yjPXB+VzBmtjIpcEv3CGBdhDDUYowStlVNMI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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