Khôltekh has asked you to investigate the area Amârbo told you about, where you will hopefully find Dar Sêkhta, and a clue as to Sêkhta's whereabouts.
'You should go to Dâr Sêkhta. Even if you cannot gain access, we may yet learn more about this key by examining the lock.
'Amârbo, if he is to be trusted at sword-point, said it was quite close to Deshûkh. South of it, if I recall correctly? That is the place to start.'
Khôltekh has asked you to look for Dar Sêkhta, and a suspicious lock there that might fit a mysterious key. According to Amârbo, it is located south of Deshûkh in Dil-irmíz.
Look for an alcove or door with an unconventional lock.
Examine the strange lock for clues as to its key.
Return to Dâr Laja with your description of the lock. Perhaps Khôltekh has a clue as to its key.
Accompany Khôltekh to his house, so he may think clearly on this key.