Lexus RX300 2003 Owner's Manual page 29

NOTICE
D Do not let the key case become bent as the key plate
may fall out or become bent also.
D The flat key is designed for emergency use only. So
do not use it regularly instead of other master keys.
11L021-2
When using a key containing a transponder chip,
observe the following precautions:
D When starting the engine, do not use the key with a
key ring resting on the key grip and do not press the
key ring against the key grip. Otherwise the engine
may not start, or may stop soon after it starts.