  Relying on precise observations for the CPD-54 810 binary system, we
investigate the robustness of the estimated age and convective core
overshooting for a system with both stars on the main sequence (MS). [...] We
adopt the SCEPtER pipeline, based on grids of stellar models computed for a
different initial chemical composition and convective core overshooting
efficiency. The base fit suggests a common age of $3.02 \pm 0.15$ Gyr, in
agreement with recent literature. This estimated convective core overshooting
parameter is $\beta = 0.09 \pm 0.01$, with a corresponding convective core mass
$M_c = 0.059^{+0.017}_{-0.021}$ $M_{\odot}$. The robustness of these estimates
were tested assuming a narrow constraint on the helium-to-metal enrichment
ratio. The chemical solution of the system changes, but the age and the
overshooting parameter are almost unchanged ($3.08^{+0.17}_{-0.14}$ Gyr and
$0.09 \pm 0.01$). In a further test, we halved the uncertainty as to the
effective temperature of both stars and again the estimated parameter shows
only small variations ($3.02 \pm 0.12$ Gyr and $0.09 \pm 0.01$). This low
variability suggests that the age of the system with both stars in the MS can
be reliably estimated at a 5\% level, but it also indicates that the power of
the investigation is probably low. [...] Despite the great increase in the
observational constraints' precision, the results support the conclusions of
previous theoretical works on the stellar parameter calibration with double MS
star binary systems.
