In this paper, throughput of two-hop wireless relay channels is studied in the finite blocklength regime. Half-duplex relay operation, in which the source node initially sends information to the intermediate relay node and the relay node subsequently forwards the messages to the destination, is considered. It is assumed that all messages are stored in buffers before being sent through the channel, and both the source node and the relay operate under statistical queueing constraints. After characterizing the transmission rates in the finite blocklength regime, the system throughput is formulated via queueing analysis. Subsequently, several properties of the throughput function in terms of system parameters are identified, and an efficient algorithm is proposed to maximize the throughput. Interplay between throughput, queueing constraints, relay location, time allocation, and code blocklength is investigated through numerical results.