SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6ec75d69d7118520b7d8230a781d1a2431785620399652b19110bf37227a385' 
  AND token = 'Yj6BateSMQQEfXj/ciskrcoNL6bvSrEkS6vsTdUisTk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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