SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e208fbf375d78d8d32318be6a3e5a042b29607157a9ff9eac477b6ea0da83303' 
  AND token = 'IfBSn47/yHMO05ksle7g7Dk9c9+y0aSSFgE+Grs++HY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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