SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '205879ea281bfdd1745ee93828dba3320cb608f7eab78736ce91c78c24679d65' 
  AND token = '1RaB5RmNA9fd43x6nXWZhEGAky1VTOgNauLyBTuZEN8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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