If I have an index on field rfrom C(10)
index on rfrom tag rfrom

In case of select statement

set exact off
lvalue='0104'

select * from ranges where alltrim(rfrom)=lvalue

is index used or it is a full scan.

My goal is to learn whether there is anything in a table with the field value for rfrom for which the statement
atc( alltrim(rfrom) , lvalue ) = 1
is true

If it is a full scan any suggestions how to organize an index which could be used in the case like this.

Thank you
Michael