  We obtain a lower bound of the distance function (MOID) between two
noncoplanar bounded Keplerian orbits (either circular or elliptic) with a
common focus. This lower bound is positive and vanishes if and only if the
orbits intersect. It is expressed explicitly, using only elementary functions
of orbital elements, and allows us to significantly increase the speed of
processing for large asteroid catalogs. Benchmarks confirm high practical
benefits of the lower bound constructed.
