SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5473a4ad4992e7d7b07ec1079922a4fa28c3861591307d748cf6d6afcd91e27b' 
  AND token = 'T5sUSwV141Ku30VKKSLGJSvy6gTVw+5D1gFWvBpZZXU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00063

JSON explain

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