These keys belong to the Boltz Exchange administrators. You can import them into your gpg keychain to verify the messages.
curl https://canary.boltz.exchange/pgp.asc | gpg --import
The message above has been signed by one of the keys associated with a Boltz Exchange administrator. Import the keys from here and then verify this message.
curl https://canary.boltz.exchange/message.txt.asc | gpg --verify
For more information, visit boltz.exchange