$ echo "ASDF {
    tmp
    plz_match
    tmp
}
string2 {
    tmp
}
string3 {
    tmp
}
" | perl -e'
local $/ = "}\n";
while ( <> ) {
    if ( /^ASDF/ && /plz_match/ ) {
        print "Matched: $_";
        ++$match;
        } 
    }                                  
print "No match\n" unless $match;
'
Matched: ASDF {
    tmp
    plz_match
    tmp
}