When a second key is locked in the car it is disabled until the car is unlocked.
I must agree with BiggyG- carrying a key in a blocking pouch kind of defeats the purpose of having keyless entry.. And it’s highly unlikely they will use a relay antenna in front of a bar where you’re having a pint after work.. Realistically- the biggest risk is in the driveway- so keeping your keeys as far as possible from doors/windows/external walls + a metal box seems like the best way to prevent this from happening.. Or living in an apartment 6 floors up, like myself
On a positive note- this is props to Volvo- finally they are as popular with thieves as the german competitors