SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '526f0a48fa12014d0e98d670768db4d3a05a41903e417335dc99c9718c10aaf2' 
  AND token = '1TgWexybBoAqZzD7+khkS0f4XCVIL4cFRjueI+y6EuI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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