SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3fa257e00da74e94f57f164a4a0c230ac70eef5e77bb07363511057a9c66fddf' 
  AND token = 'XusjA/fMoPhOvthSUVlmtZAOVXuZ8r+V5aufqyoiXvs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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