How to install a GPG keys

export KEY=648ACFD622F3D138 && sudo gpg --no-default-keyring --keyserver hkp://keyserver.ubuntu.com:80 \
  --keyring /usr/share/keyrings/${KEY}-archive-keyring.gpg --recv-keys ${KEY}

then add [signed-by=/usr/share/keyrings/${KEY}-archive-keyring.gpg] to a corresponding .list file in /etc/apt/sources.list.d/ as following

deb [arch=amd64 signed-by=/usr/share/keyrings/648ACFD622F3D138-archive-keyring.gpg] http://httpredir.debian.org/debian/ sid main contrib non-free

apt-key is a deprecated command, do not use it.

sudo apt-key adv --refresh-keys --keyserver hkp://keyserver.ubuntu.com:80