Thank you very much for the detailed response.
Do you expect symmetric keys or asymmetric keys?
Random data that is rotated multiple times a day
Have you any preferences on how keys are identified?
No preference. The keyid is random data, too.
My session ticket encryption keys are (cryptographically) random data, and are rotated multiple times a day.
You can see the sample shell script one-liner at https://redmine.lighttpd.net/projects/lighttpd/wiki/Docs_SSL#Session-Tickets
It creates random data in a binary structure that includes activation and expiration times.
Rotating the session ticket encryption key multiple times a day increases the security posture for perfect forward secrecy. In contrast, I am prohibited from regenerating certificates quite so frequently from public CAs, e.g. Let's Encrypt.
Also, in some TLS libraries (openssl, mbedtls, wolfssl), I can keep a (short) history of overlapping STEKs as I rotate them so that most recent session tickets can be validated and sessions resumed, while renewing recently-expired session tickets. (I have not evaluated TLS libraries for how complex it would be to manage multiple server certificates for the same server identity, with different, overlapping periods of validity.)
If all of the session ticket encryption keys need to be expired, I can do so nearly instantly, at the cost of invalidating resumption requests for a short period of time afterwards, causing an extra round-trip upon connection establishment. Expiring these session ticket encryption keys is independent of the server identity (the certificate).
I hope that I have explained some benefits of keeping the STEK separate from the server certificate.
The way that NSS ties the STEK to the server public key is an interesting alternative -- not without its own tradeoffs -- to solve the problem of STEK distribution across a server farm.
Thus far, these are the only generic mechanisms I have heard about for session ticket encryption key distribution, besides custom solutions referenced in blogs by CDN providers.