SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50fc6a50849fd80a671dd6b5a263d76c676a918a47258db3c9ca7eae0fd47e42' 
  AND token = 'N0nP7IIiqUa2FJqDOB/+3rigzISL/WX5x/RgLzQoKGY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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