SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '70c188830b5405e2fdbc3193d7f3028893ce50d43956bee3d36217e286a78e88' 
  AND token = 'nzkwsPrSWS4njyZVmirB7GP06LY3DpXAJzCsjKoCDmo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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