SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '98f03ed8b324c0eccbd33e377d9da33e6708b9e3d8dd9dd5240627b157b651b8' 
  AND token = 'fioLShaTZe5uUTwFmumjiXh0jwVPXU+V2ZyNpDKky84=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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