Query related to secure telemetry pings needs optimization

A query associated with collecting security job telemetry is taking a long time to complete and may require optimization.

• Scan type 6 db lab (8 sec): https://gitlab.slack.com/archives/CLJMDRD8C/p1602091355184000
• Scan type 5 db lab (8 min): https://gitlab.slack.com/archives/CLJMDRD8C/p1602088973181300

Query:

EXPLAIN SELECT MIN(“security_scans”.“build_id”) 
  FROM “security_scans” 
  INNER JOIN “ci_builds” ON “ci_builds”.“id” = “security_scans”.“build_id” AND “ci_builds”.“type” = ‘Ci::Build’ 
  WHERE “security_scans”.“scan_type” = 6 
  AND (“ci_builds”.“retried” = FALSE OR “ci_builds”.“retried” IS NULL) 
  AND (“ci_builds”.“status” IN (‘success’))

Comments resulting in this issue: !43763 (comment 425124585)

References #229541 (closed)