SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '82e679512fabfeb0a492211762044d9b69c6fc5963721e8ffc1d64cbc98892af' 
  AND token = 'KRG6veXlUVmBx0mHVWIDQVVGff7zrSzvJJwOz7K7Rc0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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