This issue is faced quite often while traveling and hiring a car and getting the similar issues.Then the person is left with no other solution except searching for a locksmith nearby.

I think wrapping it in aluminium foil before putting it in the lock box might work as it should reflect the (presumably) infra red signal.

Another option is to take it with you. I put my smart key in an Aquapac and attach it to the loop in my boardshorts. I’ve used it surfing and bodysurfing and never had any issues.
https://aquapac.net/store/shop/aquapacs-on-sale/waterproof-itunes-case-…

The missus!

I used a surf lock for about 5years until I inadvertently left it beside my car after a surf. I then purchased without any research an O + E super strong key safe. It was as stated super strong however it has push buttons not tumblers. The problem with push buttons is that the code numbers can be entered in any order as the mechanism recognises the numbers not the order they were entered.
I then did my research found this article and comments, went to the locksmith and got a door only key cut for $15. I now either use a lanyard when wearing a wettie or use the the key fob of my leggie.
Much more secure than any key safe. Even if u hide the key somewhere on ur car the car can't be stolen as the key won't start the car.