وَبِـ«مَتَى» عَنِ الزَّمَانِ مَاضِيًا كَانَ أَوْ مُسْتَقْبَلًا
Matā asks about time, whether past or future.
مَتَى سَافَرْتَ؟
When did you travel?
مَتَى تُسَافِرُ؟
When will you travel?
Both require a temporal answer. The verb and context specify whether the event is already past or yet to come. Matā itself is not restricted to futurity.
QuestionTemporal orientationInformation sought
Matā kharajta?PastTime of past departure
Matā takhruju?FutureTime of forthcoming departure
Ayyāna yawm al-dīn?FutureTime of the momentous Day