Restore an older version of iCloud keychain
I just ran into the same situation and unfortunately no you cannot restore iCloud keychain from your own backup.

See Apple's support note on the topic https://support.apple.com/kb/PH20120, specifically:


  Passwords stored in the iCloud keychain are encrypted and stored on your computer and can’t be copied. 


As you, I tried copying other keychain files and 'keychain-db' files, but none of the iCloud passwords were contained in those.