SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '43e1f0a43f057b80f7d310bba9d5a60d985be1ec4115adbd795fd0da11fe920d' 
  AND token = 'b8vsS0EsGlMU5avo7uMTZxOdXShjTJUvxXnJnjWQstQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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