No it's not in any DB, but after deeper look I can see that on classic AMD this information is present. Try to execute:
rcmd show ssldecr certs | grep -e "Subject:" -e "Not After"
This should give you the necessary info that you should process then with Linux tools to get it somewhere out ...
Technically, the private keys DCRUM holds do not expire (which is why we can't report this), it's the public certificate that has an expiry date on it.
Again technically a new certificate could be issued with the same private key - it's poor practice to do so.