SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'be4db66f1277acc9ac1485d82fcfda8d79ff0335fa2a3b5e94afd962c299248b' 
  AND token = 'WiqyoGvpb3CndTaXzZ7J+98q6V0wnM5XWHlvgpxjJ/E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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