CREATE INDEX "AccountDocument" ON "Documents" USING btree ("Account" NULLS LAST, "Document" NULLS LAST)
WHERE ("Account" IS NOT NULL OR "Document" IS NOT NULL);

CREATE INDEX "AccountUserDocument" ON "Documents"  USING btree ("Account", "User", "Document")

SELECT *
FROM "Documents"
WHERE "Account" = 1
AND "USER" = 'dd758b54-55b3-442a-804b-8a3d311432ba'::UUID 
AND "Document" = 2

"Index Scan using "AccountDocument" on "Documents"  (cost=0.29..8.31 rows=1 width=73) (actual time=0.016..0.016 rows=0 loops=1)"
"  Index Cond: ("Document" =2)"
"  Filter: (("Account" =1) AND ("User" = 'dd758b54-55b3-442a-804b-8a3d311432ba'::uuid))"
"  Buffers: shared hit=2"
"Planning time: 1.026 ms"
"Execution time: 0.039 ms"

"Index Scan using "AccoutUserDocument" on "Documents"  (cost=0.28..8.30 rows=1 width=73) (actual time=3.626..3.626 rows=0 loops=1)"
"  Index Cond: (("User" = 'dd758b54-55b3-442a-804b-8a3d311432ba'::uuid) AND ("Document" = 2))"
"  Filter: ("Account" = 1)"
"  Buffers: shared hit=73"
"Planning time: 0.946 ms"
"Execution time: 3.652 ms"