SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '43ac8ae8853411efd6a251f6fe9bd253cd0e1d24db392a1b72d59e382e761335' 
  AND token = '8V7dBB3zVDwJ9NH+7usSgBHQvtAwhWaLHqAD5kwwOj4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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