SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '681fc879bc65aa9f8a2d5ce100275af3292061a4f894947a3edb01fdfcf84b08' 
  AND token = 'L/NP7c8WEKST0DiNnLElXjNZqHLwA0dGUDcUAlkM2m0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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