Thermal rate constants for a one-dimensional model of a reactive collision involving a transient resonance are calculated by using autocorrelation functions of the flux operator in a finite basis set representation [Miller, Schwartz, and Tromp (MST), J. Chem. Phys. 79, 4889 (1983)] and performing either integration over time (MST) or Pade extrapolation to zero of an energy parameter [Lefebvre, Ryaboy, and Moiseyev, J. Chem. Phys. 98, 8601 (1993)]. The two procedures prove to be equally successful. We observe that in the time dependent approach, the correlation function of the reactive flux operator shows, as expected, damped oscillations with a period which slightly depends on the temperature. However, these oscillations are decaying on a time scale that is significantly shorter than the resonance lifetime. This finding shows that the flux-flux correlation function approach is applicable to calculations of thermal rate constants for reactions which proceed via formation of intermediate complexes as well as to studies of short time direct reactive processes.