  We report on a search for continuous gravitational waves (GWs) from NS 1987A,
the neutron star born in SN 1987A. The search covered a frequency band of
75-275 Hz, included a wide range of spin-down parameters for the first time,
and coherently integrated 12.8 days of data below 125 Hz and 8.7 days of data
above 125 Hz from the second Advanced LIGO observing run. We found no
astrophysical signal. We set upper limits on GW emission as tight as an
intrinsic strain of $2\times10^{-25}$ at 90\% confidence. The large spin-down
parameter space makes this search the first astrophysically consistent one for
continuous GWs from NS 1987A. Our upper limits are the first consistent ones to
beat an analog of the spin-down limit based on the age of the neutron star, and
hence are the first GW observations to put new constraints on NS 1987A.
