I have two possible queries, both giving the result set I want.

Query one takes about 30ms, but 150ms to fetch the data from the database.

SELECT 
    id
FROM 
    featurevalues as featval3
WHERE 
    featval3.feature IN (?,?,?,?) 
AND
    EXISTS
    (
        SELECT
            1
        FROM
            product_to_value,
            product_to_value as prod2,
            features,
            featurevalues
        WHERE
            product_to_value.feature = features.int
        AND
            product_to_value.value = featurevalues.id
        AND
            features.id = ? 
        AND
            featurevalues.id IN (?,?)
        AND
            product_to_value.product = prod2.product
        AND
            prod2.value = featval3.id
    )

Query two takes about 3ms -this is the one I therefore prefer-, but also takes 170ms to fetch the data.

SELECT 
    (
        SELECT
            prod2.value
        FROM
            product_to_value,
            product_to_value as prod2,
            features,
            featurevalues
        WHERE
            product_to_value.feature = features.int
        AND
            product_to_value.value = featurevalues.id
        AND
            features.id = ? 
        AND
            featurevalues.id IN (?,?)
        AND
            product_to_value.product = prod2.product
        AND
            prod2.value = featval3.id
    ) as id
FROM 
    featurevalues as featval3
WHERE 
    featval3.feature IN (?,?,?,?) 

The 170ms seems to be related to the number of rows from table featval3. After an index is used on featval3.feature IN (?,?,?,?), 151 items "remain" in featval3.

Is there something obvious I am missing regarding the slow fetching? As far as I know everything is properly indexed.. I am confused because the second query only takes a blazing 3ms to run.