SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c8f11c662a0ef9206e6b454a90617cdcd527468e7520b08583fb818813fbc57' 
  AND token = 'GYYG+AsD6Z/A/qt+0ctX3FxFuvVcI0sSnmVTvxwdGIg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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