I tried your code and got partial optimization. I then created a DBC and added the table to it. Ran SDT Explorer to create all the extensions. Then ran the following code to have SDT reindex. I still got partial optimization on the query.

close all
open database gdtest
set database to GDTest
set procedure to program()
oMeta = NewObject("DBCXMgr", "DBCXMgr.VCX")
oMeta.SetDataBase(dbc())
llRetval = oMeta.oSDTMgr.Reindex('', .f., .t.)
close table all
sys(3054,1)
select ctest from test where mkup() = 'A' into cursor curtest
sys(3054,0)
close tables all
release procedure program()