SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c33df88e80fa7eb982ffb46dd611044a81f066726a79df1470df88521d814f7' 
  AND token = 'K1Ihw3y8wu/YaNqCbztzaie7rC3HHiqubHuBVEATP/w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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