sed -n 's#ssh-rsa.*OLD_KEY_ID#NEW_KEY# p' .ssh/authorized_keys
sed -n '#ssh-rsa.*KEY_ID# p' .ssh/authorized_keys
sudo find . -maxdepth 3 -name "authorized_keys" -exec sed -i.old 's#ssh-rsa.*OLD_KEY_ID#NEW_KEY#' {} \;
sudo find . -maxdepth 3 -name "authorized_keys" -exec sed -i.old '#ssh-rsa.*KEY_ID# D' {} \;
Tip: use a bash variable e.g. $NEW_KEY to use in your commands. Note that you'll need to use double instead of single quotes in the sed command.