SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3918495800d22f05426f270a43a5da786c9ebf8c6c5dd00fa589a59af3ec72b2' 
  AND token = 'jBcYCrmgb9+rTVjId3Ot3C0H5hXBHbeaMDyIYAVFMGI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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