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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b3e36ce7aa7fa7ab6dd5c0dd50fb82ad92f1e2a72c4efef950cac3c2a03087d' 
  AND token = 'nKmP2M3IqVmgeuGVaMubn+GoRJmqYnP3au3ajBqXvaU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}