Open a termınal <ctrl><alt><t>
Into the terminal enter
setxkbmap -option grp:switch,grp:alt_shift_toggle,grp_led:scroll ru,us
This sets the <alt><shift>
keys to toggle between the US and Russian keyboards.
will switch between the two.
If you don't like it
turns it off, disabling the key combination with the keyboard staying on the last setting.
If you like what you see
echo "setxkbmap -option grp:switch,grp:alt_shift_toggle,grp_led:scroll ru,us" >> ~/.bashrc
will make this command/key combination available all the time.