Lexus did not make the GX470 in 2010. The last year of production was 2009. So, no, there is not a valet key for the 2010 Lexus GX470.
Only the dealership can cut a Lexus key because the chip that allows the key and car to communicate is part of the metal part of the key.
CR1616
CR1616
Open the key fob, remove the battery and look and see what size it is.
The key battery for the ls400 is PN# br1216 www.lextechautomotivellc.com
Open it up and check and see.
Panasonic CR 1616
Car alarm in Lexus ES300 started going off at random when car was parked, not running. I changed the key fob battery (flat watch battery) with a new battery and it fixed the problem.
By inserting the key in the door lock and turning.
3 button fob 2003 onwards cr1616
Open the key fob and see what battery it contains.