SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e9bc1d40736add5100002b2715851d823d964c7fb96aac311483ab26455a0c67' 
  AND token = 'vXUkw6fL8uzH9l+UWxbYOgdXq1YZOkYiBgSUVUHqRSM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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