Return raw true boolean value when there's a coicidence on the bucket

Well I did this query in order to return true if there’s a coicidence on my bucket:

SELECT RAW CASE COUNT(1)
  WHEN 1 THEN TRUE
  ELSE FALSE
END
FROM `Bucket_XXX` AS b
WHERE b.type="donut"
  AND b.deleted = false
LIMIT 1;

Well I’m trying to use the count in order to return true if there’s a coicidence but it always return false, althought the query is working normal only with the select

It works for me

SELECT RAW CASE COUNT(1) WHEN 1 THEN TRUE ELSE FALSE END FROM [{"a":1}] AS d WHERE d.a = 1;

Simplified one will be

SELECT RAW COUNT(1) == 1 FROM [{"a":1}] AS d WHERE d.a = 1;

Count is aggregate, can you tell me how using and what not working.
Aggregate means it need to process all the qualified documents, LIMIT 1 applied on aggregated results.

Is the following helpful.

EXISTS(SELECT RAW 1
       FROM `Bucket_XXX` AS b
       WHERE b.type="donut" AND b.deleted = false
       LIMIT 1)

I see the issue seems to be that it need to process all the qualified documents, so in this case I need a query to check if there’s at least one coicidence in order to return true; is it possible to not evaluate all the coicidences? in order to optimize it?

SELECT EXISTS(SELECT RAW 1
       FROM `Bucket_XXX` AS b
       WHERE b.type="donut" AND b.deleted = false
       LIMIT 1)

Subquery stops once it produced one document.