Some GPS satellites are currently broadcasting the current time with a cryptographic hash to prove that the broadcast time is the actual time[1] and authenticate the satellite as not being tampered with. It's live right now. So, as long as you can use witness encryption to prove that the broadcasted hash and signal is after a certain time, you can have true time locked encryption.

The problem is that the witness encryption is extremely inefficient with today's knowledge.

So, as long as you can trust a space agency to broadcast the current time to the entire world, you'll be fine.

[1]: https://www.gsc-europa.eu/galileo/services/galileo-open-serv...