SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b7cb118402a4f80d846e50d99b6be97115f870578aa71b82768e34c98531e3b' 
  AND token = 'fBhCe+igOjV6Wr7PtT/h7RkxH0O5lajeRLXMlZml+sI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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