I have an api request to my backend api to check whether a license key is valid or not, but the request is not working properly.

page.tsx

'use client';

import React from 'react'
import { useState } from 'react';
import { Button } from '@components/ui/button'
import { Card, CardContent, CardDescription, CardFooter, CardHeader, CardTitle } from '@components/ui/card'
import { Input } from '@components/ui/input'

const page = () => {

  const [inputValue, setInputValue] = useState('')
  
  const checkKey = async () => {
    console.log(`Param: ${inputValue}`);
    const res = await fetch('/api/auth/checkkey', {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
      },
      body: JSON.stringify({
        key: inputValue,
      }),
    });
    const data = await res.json();
    console.log(data);
  };

  const closeTab = () => {
    window.close()
  }

  return (
    <div style={{ display: 'flex', justifyContent: 'center', alignItems: 'center', height: '100vh' }}>
      <Card className="dark">
        <CardHeader>
          <CardTitle>License Key</CardTitle>
          <CardDescription>Please enter your license key to access /bleeds eye</CardDescription>
        </CardHeader>
        <CardContent>
        <Input value={inputValue} onChange={(e) => setInputValue(e.target.value)} />
        </CardContent>
        <CardFooter>
          <Button className="dark mr-3" onClick={checkKey}>Check Key</Button>
          <Button className="dark" variant="outline" onClick={closeTab}>Cancel</Button>
        </CardFooter>
      </Card>  
    </div>
  )
}

export default page

route.js

 import { connectToDB } from "@utils/database";
import Keys from "@models/keys";

export const POST = async (request) => {
    try {
        connectToDB();

        const token = request.body.key

        console.log(`Key: ${token}`);

        const newKey = new Keys({
            key: token,
            expires: new Date(Date.now() + 30 * 24 * 60 * 60 * 1000),
            uses: 100,
            suspended: false,
        });

        await newKey.save();

        return new Response(JSON.stringify({ success: true }), {
            headers: { "Content-Type": "application/json" },
        });
    } catch (error) {
        return new Response(JSON.stringify({ success: false + error }), {
            headers: { "Content-Type": "application/json" },
        });
    }
};

I have tried troubleshooting for hours but nothing has worked.