We present an ultracompact plasma-based method to measure spatial and temporal concurrence of intense electron and laser beams nonintrusively at their interaction point. The electron beam couples with a laser-generated seed plasma in dependence of spatiotemporal overlap, which triggers additional plasma production and manifests as enhanced plasma afterglow. This optical observable is exploited to measure beam concurrence with $\sim 4\mu m$ spatial and $\sim 26.7\mathrm{fs}$ temporal accuracy, supported by auxiliary diagnostics. The afterglow interaction fingerprint is highly sensitive and enables ultraversatile femtosecond-micrometer beam metrology.