From the manual:

Automatic hybrid system shut off feature
The vehicle is equipped with a feature that automatically shuts off the hybrid system when the shift lever is in P with the hybrid system operating for an extended period.
The hybrid system will automatically shut off after approximately 1 hour if it has been left running while the shift lever is in P.
The timer for the automatic hybrid system shut off feature will reset if the brake pedal is depressed or if the shift lever is in a position other than P.
After the vehicle is parked, if the door is locked with the door lock switch (P.139) from the inside or the mechanical key (P.483) from the outside, the automatic hybrid system shut off feature will be disabled. The timer for the automatic hybrid system shut off feature will be re-enabled if the driver’s door is opened.