SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20b97ece457885c8309cd9577f96c1f2710217c52c1fb3049ff92ddf9dacfa03' 
  AND token = 'VtPmQsuREz7G0ISfLocSs8AF0qJDfatMYDUXtAue7P0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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