SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '25dffd79513df8b5c677b594b25a65270452d914b6a8d43cc102dce5abbe3966' 
  AND token = '81mxenbpYE3m688FNXkYgmClhi8hzNCfoA1xlPTc6p8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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