RFC 3815 defines MPLS-LDP-STD-MIB. This MIB is used to query statistics of MPLS and LDP.
The OID of the root object is:
iso(1).org(3).dod(6).internet(1).mgmt(2).mib-2(1).transmission(10).mplsStdMIB(166).mplsLdpStdMIB(4)