SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f806e6a38c7983180c6c8617a25cef43fea6ad5fdcdcf1c951a82fe5508aab31' 
  AND token = 'fd2UOaImgieGQTZqZa4bkiaZVYuDAgOadhB+nSFUrUw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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