Another approach is to use the power of Q... er, quotemeta to unmajick those pesky regex metacharacters.

>perl -wMstrict -le
"my $s = '85|mat@com';
 print qq{'$s'};
 ;;
 my $sep = '|';
 my ($key, $email) = split qq{\Q$sep\E}, $s;
 ;;
 print qq{key '$key'   email '$email'};
"
'85|mat@com'
key '85'   email 'mat@com'
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