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SELECT 
  1 
FROM 
  tmall_lock_keys 
WHERE 
  key_id = '9412dd6c27c9fd796bb292f5a490a2fbc62494372e081cfaacf16e6af99b8952' 
  AND token = 'NT9ep+/tx7z9JiQzoqqL5uXkyfibQxocf15F9Scgay4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00759

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}