In my opinion, the link to Parsing a file with parentheses to build a hash is relatively suitable, as it points to a very similar problem, extracting terms between ( and ) instead of { and }.

Depending on the nature of your data, you might be able to simply extract all pairs of {...} and then check those for your keywords. A very simplicistic parser would be:

my $line= 'abc ... {abc} ... abc';
my @terms= $line =~ /\{(.*?)\}/g;
for my $bracketed (@terms) {
    print "$bracketed matches $1"
        if ($bracketed =~ /(abc|nop)/);
};
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This does not care for nested sets of brackets. For parsing nested sets, see the linked node.