Lock Pick
From WikiRaider
The Lock Pick is a Gear item in Rise of the Tomb Raider. It can be used to open certain doors, Lockers, and Strongboxes.
A makeshift lock pick that allows Lara to open padlocks found on some chests or doors.
Survival Guide
Lara has to first acquire the Lock Pick, it is not part of her basic gear. After finishing the Mission Communications Breakdown the Remnant General gives it to her.
To use the Lock Pick Lara has to stand near the object she wants to open and hold the Interaction button (Xbox: X) for several seconds.