Optically interfaced solid-state spins enable quantum technologies with unprecedented capabilities for sensing, communication, quantum-coherent memories, and exploration of fundamental physics. Hexagonal boron nitride (h-BN) hosts pure single-photon emitters that have shown evidence of optically detected electronic spin dynamics. However, the electrical and chemical structures of these optically addressable spins are unknown, and the nature of their spin-optical interactions remains mysterious. Here, time-domain optical and microwave experiments are used to characterize a single emitter in h-BN exhibiting room temperature optically detected magnetic resonance. Using dynamical simulations, transition rates are constrained and quantified in the model, and optical control protocols are designed that optimize the signal-to-noise ratio for spin readout. This constitutes a necessary step toward quantum control of spin states in h-BN.