Nuclear magnetic resonance (NMR) measurements under a pressure of 3.0 GPa were performed for a prototypical iron-based high-T-c superconductor LaFeAsO1-xHx (x=0.2). At ambient pressure, this compound has superconducting (SC) double domes with the T-c minimum of 26 K at x=0.2 in the electronic phase diagram. Pressure application merges the double domes into a single dome, and the T-c minimum at x=0.2 goes up to 45 K, the T-c maximum, at 3.0 GPa. Despite that T-c enhancement under pressure was confirmed from the As-75 relaxation rate divided by temperature (T), 1/T1T around T-c, 1/T1T at high temperatures was almost the same with that at ambient pressure and hardly showed Cure-Weiss behaviour. These features are also seen for 14% F-doped LaFeAsO1-xFx, suggesting that spin fluctuations are not essential to achieve high T-c over 45 K.