It looks like this has been doubly serialized. It expands to an array with a single element, and that element is a serialized associative array. So you need to do:
$temp = unserialize($data);
$result = unserialize($temp[0]);
var_dump($result);
Result:
array(6) {
["rowid"]=>
string(32) "94ca9ee0c4e3184b50e89e82f80332fb"
["id"]=>
string(2) "68"
["qty"]=>
string(1) "1"
["price"]=>
string(2) "20"
["name"]=>
string(5) "Bread"
["subtotal"]=>
int(20)
}
If there can be more that one element in the top-level serialized array, use array_map to unserialize all of them:
$result = array_map('unserialize', $temp);
$result will now be a 2-dimensional array.
I'm not sure why you stored your data this way. Why not just serialize the original 2-d array all at once, instead of nesting them?