SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc8c0f8a483252731beac82d8783f10d0a6e39da8ca164872ad361031765890b' 
  AND token = '3dZMP6QKQt7qwSTQw9WKg+nbWxEH9UpVDici3GjNoNk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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