SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2b690a3d0637144483628590d188a9bc7f7514624b10954a8186e076251a588d' 
  AND token = 'CC85oBL9XHe9JNej1rpyokbOyGxi3LCGTNpqtFqXttY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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