SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b49833d1a25d53bcaaff3446a5ff2ddeec402e8d89e664a60759b08fd505d454' 
  AND token = 'nPMXe2eF13oz6Os5pQrinwNnLE5yeByB42AodGpO5HE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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