SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3df5fddcfa3ebee7aeb7b0931017183770603c39a7dcf432e852fa2bea43a481' 
  AND token = 'Jc7f9vzNKXe42n7EI4OzcOxYTeow+nvVhDPF3x2RDlU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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