Have you tried very gently tugging the steering wheel to one side, then very gently turning the key? Try blowing some graphite powder into the lock. If this fails RaymanSean's suggestion of heat applied to the tumbler won't hurt as this may be all that is needed & worth a try.
Any sort of force should be avoided. If you've used excessive force on the key the tumblers in the lock barrel may be damaged.
You may have to consider removing the lock barrel which may require drilling the mount posts out. Good luck.
This thread/write-up may help: viewtopic.php?f=1&t=34472&p=159968&hilit=v70+ignition+lock#p159968
Current cars: 1995 850, 2000 V70 non turbo, 2001 V70 XC project, 2002 XC70
What we used to own:1987 740 sedan, 2002 S60AWD, 1989 740 turbo wagon, 1985 760 V6, 1995 850 wagon, 1999 V70 project car.
In forum posts please call me Mike