Confused about the index on the Sql server

Question

I have the following table structure:

When I set the column Idas the primary key, it automatically creates an index with a name PK_TestIndexTbl (Clustered)in the Indexes folder. My table contains about 1,300,000 records, and when I execute the following query, it takes about 5 seconds:

SELECT [Id], [Name], [Family], [Score]
FROM   [TestIndexTbl]

But when I delete the primary key from the table and, of course, delete the index, I expect my query to take more than 5 seconds, because now I do not have an index. But it does not matter, and I get the result after 5 seconds, as before. Why?

: ? , ? Where . :

SELECT [Id], [Name], [Family], [Score]
FROM   [TestIndexTbl]
where Id = 602145

Answer 1

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Answer 2

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SELECT [Id], [Name], [Family], [Score]
FROM   [TestIndexTbl]
WHERE Id = 602145

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Answer 3

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Answer 4

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