  Context: Gamma-ray bursts are cosmological sources emitting radiation from
the gamma-rays to the radio band. Substantial observational efforts have been
devoted to the study of gamma-ray bursts during the prompt phase, i.e. the
initial burst of high-energy radiation, and during the long-lasting afterglows.
In spite of many successes in interpreting these phenomena, there are still
several open key questions about the fundamental emission processes, their
energetics and the environment. Aim: Independently of specific gamma-ray burst
theoretical recipes, spectra in the GeV/TeV range are predicted to be
remarkably simple, being satisfactorily modeled with power-laws, and therefore
offer a very valuable tool to probe the extragalactic background light
distribution. Furthermore, the simple detection of a component at very-high
energies, i.e. at $\sim 100$\,GeV, would solve the ambiguity about the
importance of various possible emission processes, which provide barely
distinguishable scenarios at lower energies. Methods: We used the results of
the MAGIC telescope observation of the moderate resdhift ($z\sim0.76$)
\object{GRB\,080430} at energies above about 80\,GeV, to evaluate the
perspective for late-afterglow observations with ground based GeV/TeV
telescopes. Results: We obtained an upper limit of $F_{\rm 95%\,CL} = 5.5
\times 10^{-11}$\,erg\,cm$^{-2}$\,s$^{-1}$ for the very-high energy emission of
\object{GRB\,080430}, which cannot set further constraints on the theoretical
scenarios proposed for this object also due to the difficulties in modeling the
low-energy afterglow. Nonetheless, our observations show that Cherenkov
telescopes have already reached the required sensitivity to detect the GeV/TeV
emission of GRBs at moderate redshift ($z \lesssim 0.8$), provided the
observations are carried out at early times, close to the onset of their
afterglow phase.
