title: What is the reason for 'Query condition missed key schema element' in AWS DynamoDb?
body: <p>Here is my code to fetch all elements that has a text as 'Make a dinner'.</p>
  <pre><code>const params = {
      TableName: 'todos',
      KeyConditionExpression: 'todoName = :t',
      ExpressionAttributeValues: { ':t': 'Make a dinner' }
    };
  
  db.scan(params, (err, data) =&gt; {
      if (err)
          console.log(err);
  });
  </code></pre>
  <p>I get this error:</p>
  <blockquote>
  <p>Query condition missed key schema element: todo_id</p>
  </blockquote>
  <p>What is the reason for this error? How to avoid it? I have only primary key in my table, no sort key.</p>