SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '834fc59ca8dd4ed4de7fb7963a26363d871bea22f490dc8fc8b723c2ad721db0' 
  AND token = '4UlrLGOdgjSoNarXvhwV6jO0jrbAlzFjQfNW+F1ojGs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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