Configuration
Hotbar Locker 0.4.0 has no editable configuration files. It does not generate a mod-specific TOML, JSON, or server configuration file.
Key binding
Change Toggle hotbar slot lock under Options → Controls → Key Binds → Hotbar Locker. Assign any available key, then select a hotbar slot and press it to toggle that slot's lock. This is a Minecraft control binding, not a Hotbar Locker configuration file. The game's controls screen manages the binding; no separate mod reload or restart is needed.
The mod has no other player- or server-editable settings. Locks are saved per player as gameplay state, rather than as configuration options.