[0]=>string == "45"
[1]=>string == "test-sample"

print_r(explode('-', $string, 2));    // take some help from the limit parameter

Array
(
    [0] => 45
    [1] => test-sample
)

$array = explode('-', $text, 2);

$str = "45-test-sample";
$arr = explode('-', $str, 2);
print_r($arr);

Array
(
    [0] => 45
    [1] => test-sample
)

<?php
  $str = "45-test-sample";
  list($a,$b) = explode('-', $str, 2);
  $arr=Array();
  $arr=['0'=>"String == ".$a,'1'=>"String == ".$b];
  print_r($arr);

Array
(
   [0] => String == 45
   [1] => String == test-sample
)