Locking level door after entering

[Cruzore]

If I understood it right, you want to be able to use a key on the second map's door so it locks? If so:
map 2 script file:
void OnStart()
{
AddUseItemCallback("", "key_3", "level_celler_1", "LockDoor", true);
}
void LockDoor(string &in asItem, string &in asEntity)
{
SetLevelDoorLocked(asEntity, true);
//If you want to remove the key also:
RemoveItem(asItem);
}