lumen array_key_exists() depreciated, then how to use the alternative like isset() or property_exists() to array?

  arrays, key, lumen, php

i’ve already trying array_key_exists(). But when it should return the expected result, lumen display error message that i need to use another php function instead of array_key_exists() like isset() or property_exists() as mentioned in this question title.

        $jsonData = "mydata.json";
        $content = file_get_contents($jsonData);
        $unsortedData = json_decode($content, true);

        //convert array to object
        $object = (object) $unsortedData;

        $key = $request->input('key');
        $keyData = "false";
        if(array_key_exists($key, $object))
            $keyData = "true";

        // usort($unsortedData,  function($a, $b){
        //     return $a['no'] > $b['no'];
        // });
        return $keyData;
        // var_dump($unsortedData);

so, which one should be used and how to use it? thanks for your help

Source: Ask PHP