Is Gnome keyring safe?
Solution 1:
There is no special trick here; you are just responsible for keeping your desktop session locked when you are not sitting in front of your computer. Otherwise people walking by could do anything to your computer, even if you are not using a keyring of any kind, including installing a secret password-sniffing program!
Get in the habit of locking your screen whenever you get up for any reason. Do it even when you are sure you are alone so it becomes rote. This is quicker if you configure a keyboard shortcut like Ctrl+Alt+L for it (launch Keyboard --> Shortcuts --> System --> Lock screen
). It would be nice if the Power control panel allowed you to lock the screen when a laptop lid is closed, but this does not seem to be an option.
And in case you forget, configure the screen to lock after a few minutes of inactivity (rather than going into a screensaver): Screen > Lock.
Solution 2:
Keyring is meant to simplify your life by remembering different secrets (passwords), which are stored encrypted using your master password as encryption key. The encryption is a protection against remote attack (or if your hdd gets stolen or similar), because secrets are not disclosed in such case. If you disable unlocking keyring at login, you get only the advantage of typing the same password, instead of many different ones.