First of all, select your version from arch archives for cuda and cuda-tools. I selected the latest 12.1 version: 12.1.1-4
Then just run these lines:
sudo pacman -U https://archive.archlinux.org/packages/c/cuda/cuda-12.1.1-4-x86_64.pkg.tar.zst
sudo pacman -U https://archive.archlinux.org/packages/c/cuda-tools/cuda-tools-12.1.1-4-x86_64.pkg.tar.zst
Now as soon as you install these packages package manager will want to update them, to disable updating these packages.