Keep a checkbox checked after submit

After i submit and the page reloads, how can i keep this checkbox checked? If it was checked by the user.

In the $checked variable, i dont need in_array, but i dont know, that what i need.

echo '<div class="sidebar_szuro_div">
                <span class="sidebar_title"><i class="fa fa-caret-down" aria-hidden="true"></i> Akció</span>';
                $gyartok = runsql_array("
                SELECT gyarto_id, gyarto_nev FROM gyarto WHERE gyarto_id in (SELECT DISTINCT termek_gyarto FROM termek WHERE termek_id IN (  SELECT   kat_kapcs_termek_id FROM  `termek_katgoria_kapcsolo` WHERE kat_kapcs_kategoria_id='$kat_id'  )) ORDER BY gyarto_nev ASC");
                if(isset($_REQUEST["csak_akcios"]))
                {
                    $default = $_REQUEST["csak_akcios"];
                }
                else
                {
                    $default = array();
                }
                echo '<div class="filters_container">';

                        $termekdarab = runsql("SELECT COUNT(termek_id) AS counted FROM termek WHERE termek_status = 1 AND termek_akcio = 1
                        AND termek_id IN (  SELECT   kat_kapcs_termek_id FROM  `termek_katgoria_kapcsolo` WHERE kat_kapcs_kategoria_id='$kat_id'  )
                        ");

                        //$checked = in_array($gy["gyarto_id"] , $default)?' checked ':''; ????
                        echo '<div class="checkbox padding_left_10 filter_div"><label><input type="checkbox"  name="csak_akcios" value="1">Csak az akciós termékek mutatása ('.$termekdarab["counted"].')'.'</label></div>';

                    echo '<div class="text-center"><button type="submit" name="filter_submit_btn" class="btn szures_btn">Mehet</button></div>';
                echo '</div>';
        echo '</div>';