A time-of-flight inelastic neutron scattering study of Ca0.4K0.6(NO3)1.4 of the temperature dependence of the dynamic structure factor revealed a clear frequency-independent signature of the glass transition at the conventional transition temperature Tg. Above Tg the data combined with our previous neutron spin echo results display two relaxation processes at well-separated frequencies. The faster process was now found to be consistent with a scaling behaviour corresponding to a critical-type slowing-down when approaching a certain temperature T0, as predicted by recent mode coupling theories. The variation of various properties consistently points to a critical temperature T0 of about 30 K above Tg = 333 K.