Since the value is all numeric, DBI/DBD might be attempting to treat it as a number instead of a string. This could be a problem since it's too large for an int unless you have a 64-bit perl. You might try explicitly binding as a string.

use DBI qw(:sql_types);
my $query="SELECT * FROM $table WHERE (ukey = ?)";
my $sth=$dbh->prepare($query);
$sth->bind_param(1, $ukey, SQL_VARCHAR);
$sth->execute();
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BTW, since you're not checking the returns, I hope you have RaiseError set.

---
print map { my ($m)=1<<hex($_)&11?' ':'';
$m.=substr('AHJPacehklnorstu',hex($_),1) }
split //,'2fde0abe76c36c914586c';
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