There are plenty of ways to search for specifictypes of items with Spotlight:
you enter a keyword (for example, ‘app’ to search for applications only, ‘event’ to search for iCal events only, and so on).
Turns out you can use a similar trick to look for items in your default keychain:
Press c-Spacebar to invoke Spotlight, then type ‘keych’ and press Enter.
Keychain Access should launch, with the keyboard focus already on its search box, ready for you to type and find what you want.
Note that this shortcut works only if your keychain is already open. By default that happens when you log in to your user account, because the passwords
for your keychain and your account are the same. But if it isn’t open – perhaps because you’ve changed your keychain password – this trick won’t work.