Due to the random movement of sensor nodes in uncontrolled mobile sensor networks, the distribution of sensor nodes may not be uniform over the area of network coverage. Querying a target space in which mobile sensors are unavailable at the time of the data request will lead to no return of the result. In this paper, this problem is referred to as sensor void problem, which leads to difficulties in data management and application design activities. We address the sensor void problem and offer solutions with a location-aware time-constrained query processing strategy. The key idea of the proposed strategy is to allow mobile sensor nodes to keep track of time validity and target location matching checks for the execution of the queries received from the base station. Programmers can specify a certain degree of time sensitivity in their queries according to their applications' semantics. We implemented the proposed mobile query processing scheme into our previously developed sensor database system. A performance evaluation shows how the proposed query processing strategy effectively handles the sensor void problem with various parameters of an uncontrolled mobile sensor network.