SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55662300a703d5991c5c546248ef36c19b519fca5924a493c9936cbeaa7bf9df' 
  AND token = 'd3jcpWUIbKzc1FoqDui1ztOvdYJ70b2wf4HttMpX/5A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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