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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8d3ffc6bc6b201992dda133df8b5587ba174e3aa4a2d67b6b8349ef33a58b750' 
  AND token = 'ND5I4oGy8ypKZL6siH7MVb4JzrkiZMDcTL6euHblQUU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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