We consider a scalar field under the effect of external magnetic field in the near-horizon geometry of the Banados-Teitelboim-Zanelli black hole with torsion and obtain quasistationary states of the system under consideration by solving the corresponding Klein-Gordon equation. We obtain exact solution of the equation and accordingly we arrive at a complex spectra. We observe that the real oscillation frequency of the modes and their decay time depend on the strength of external magnetic field besides the parameters of geometric background. We see that amplitude of the real oscillation modes decreases and decay time of the modes becomes longer as the strength of the external magnetic field increases. The results indicate that the geometric background is stable under such a perturbation field.