If the keys are not worn significantly suspect a worn ignition cylinder. Here is how to change the cylinder if bound up.
Ignition Switch Lock Cylinder Replacement Removal Procedure
Important: Perform the body control module (BCM) theft deterrent relearn procedure whenever you replace the ignition switch lock cylinder.
Ignition and Start Switch Replacement Removal Procedure
Important: You cannot remove the PasslockTM electrical connector until the lock cylinder is removed.
Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
Tighten Tighten the bolts to 10 N·m (89 lb in).