SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ddd44177e10adf84d1bc68e8d18050f9e8de4de60e3968c63727466d3d3f355' 
  AND token = 'DOQDZnjwgdJOWPypSZgj6TaVo8i14BJR0jmN1CD4OGI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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