Woocommerce custom add to cart with unique id - php

Question

I am not that proficient at coding so please bear with me.
I have this custom add to cart code:
public static function add_to_cart( $params, $uid ) {
$data = self::get_calc_data($uid);
foreach ($data as $calc_id => $calc_data) {
$product_id = isset($calc_data['woo_info']['product_id']) ? $calc_data['woo_info']['product_id'] : null;
if ( $product_id && intval($product_id) === intval($params['woo_info']['product_id']) ) {
$meta = [
'product_id' => $product_id,
'item_name' => isset($calc_data['item_name']) ? $calc_data['item_name'] : '',
];
if(!empty($calc_data['descriptions']) && is_array($calc_data['descriptions'])) {
foreach ($calc_data['descriptions'] as $calc_item) {
if ( $calc_item['hidden'] === true ){
continue;
}
if ( strpos($calc_item['alias'], 'datePicker_field_id_') !== false ) {
$val = $calc_item['converted'] ? ' ('. $calc_item['converted'] . ') ' . $calc_item['value'] : $calc_item['value'];
}else{
$labels = isset($calc_item['extra']) ? $calc_item['extra']: '';
if ( (strpos($calc_item['alias'], 'radio_field_id_') !== false
|| strpos($calc_item['alias'], 'dropDown_field_id_') !== false)
&& key_exists('options', $calc_item) ) {
$labels = CCBWooCheckout::getLabels($calc_item['options']);
}
if ( strpos($calc_item['alias'], 'multi_range_field_id_') !== false
&& key_exists('options', $calc_item) && count($calc_item['options']) > 0 ) {
$labels = key_exists('label', $calc_item['options'][0]) ?
$calc_item['options'][0]['label']: '';
}
$val = isset($labels) ? $labels . ' ' . $calc_item['converted'] : $calc_item['converted'];
}
$meta['calc_data'][$calc_item['label']] = $val;
}
}
/** add totals data */
if( !empty($calc_data['ccb_total_and_label']) && is_array($calc_data['ccb_total_and_label']) ) {
$meta['ccb_total'] = $calc_data['ccb_total_and_label']['total'];
}
WC()->cart->add_to_cart($product_id, 1, '', array(), array('ccb_calculator' => $meta));
}
}
}
It adds simple item from a plugin into Woocommerce Cart. I am trying to add a unique ID for every added item so that I can add multiples of the same item and they would show as unique items in the cart.
I was trying to create the unique ID with
public static function add_custom_cart_item_data( $cart_item_data, $cart_item_key ) {
$cart_item_data[custom_data]['unique_key'] = md5( microtime().rand() );
return $cart_item_data;
}
and then use the $cart_item_data; changing the 'product_id' => $product_id, to 'product_id' => $cart_item_data, but sadly this doesn't seem to work. What am I doing wrong?
Really appreciate all your help!