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SELECT 
  1 
FROM 
  tmall_lock_keys 
WHERE 
  key_id = '42a33657432577cde6e73cd648001d006c38f5539d471e23ef44c0dbac4ec00d' 
  AND token = 'DxWpHA96TqQfpc9BpxDAFOC5THh1ERKtvzgZGk8bR+g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00769

JSON explain

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