SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c922ad06017371c3d960e5f859553b2f46317d7b98d045c21e2129e8f19df2d3' 
  AND token = '2SfIxqiNsHmGyrYaTC+Qe/yXDEjSFoIF5xeajyPVnN0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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