def METHOD_NAME(engine: Connectable) -> Mapping[CRS, Type[SpatialIndex]]:
    """
    Return a CRS-to-Spatial Index ORM class mapping for indexes that exist in a particular database.
    """
    out = {}
    with Session(engine) as session:
        results = session.execute(select(SpatialIndexRecord.srid))
        for result in results:
            epsg = int(result[0])
            spindex = spindex_for_epsg(epsg)
            crs = CRS(f'EPSG:{epsg}')
            out[crs] = spindex
    return out