Prevent OpenVPN from asking token password (Linux)

I want to wrap openvpn into systemd unit as in https://gist.github.com/brauliobo/94ac38fe2695f405df2cbd8d0a1da207. Exactly, I want to tunnel into VPN only traffic from the browser.

But I have a USB token, and every time I run OpenVPN it asks me ‘Enter <…> token password: ‘, and systemd service is not displaying it.

Can I prevent OpenVPN from asking this password? The option “askpass token.txt” in openvpn conf file doesn’t help.

Or is there a way for systemd unit to get my password from input and send it to openvpn?