The Seyfert 1.9 galaxy MCG-05-23-016 has been shown to exhibit a complex X-ray spectrum. This source has moderate X-ray luminosity, hosts a comparably low-mass black hole, but accretes at a high Eddington rate, and allows us to study a supermassive black hole in an early stage. Three observations of the INTEGRAL satellite simultaneous with pointed Swift/XRT observations performed from December 2006 to June 2007 are used in combination with public data from the INTEGRAL archive to study the variability of the hard X-ray components and to generate a highquality spectrum from 1 to 150 keV. The AGN shows little variability in the hard X-ray spectrum, with some indication of a variation in the high-energy cut-off energy ranging from 50 keV to ≫100 keV, with an electron plasma temperature in the 10 - 90 keV range. The reflection component is not evident and, if present, the reflected fraction can be constrained to R < 0.3 for the combined data set. The AGN exhibits a remarkably high Eddington ratio of Lbol/LEdd > 0.8 (or Lbol/LEdd > 0.1, if we consider a higher mass of the central engine) and, at the same time, a low cut-off energy around 70 keV. Here we discuss in detail the mass estimate and its implications for our understanding of this Seyfert galaxy. Objects like MCG-05-23-016 might indicate the early stages of super massive black holes, in which a strong accretion flow feeds the central engine.