lock screen time

Show the current setting:

gsettings get org.gnome.desktop.session idle-delay

gsettings get org.gnome.desktop.screensaver lock-delay

gsettings get org.gnome.desktop.screensaver lock-enabled

Set the time in seconds:

gsettings set org.gnome.desktop.session idle-delay 3600

Or disable the screensaver totaly:

gsettings set org.gnome.desktop.screensaver lock-enabled false