The main keyserver that GnuPG has been using for a very long time, is no more.
So you need to change your ~/.gnupg/gpg.conf file to have:
keyserver hkps://keyserver.ubuntu.com
To have a working keyserver again, until the next upstream release of GnuPG fixes this.
PS: Add the same to /etc/pacman.d/gnupg/gpg.conf for pacman-key to also use the server.