SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '86c6b67ce1bc4a975b28360f2d8d48ca14e48003d301b5c8fa9f37b85fd5520d' 
  AND token = '9b/KLzrKCfmmAoFbzFFMwYEE/VfkFrmo0LXq/EPqZhw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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