SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b819511fa0590b0ebc7e890012f68d1e97a16ae0f6959cee8993e509193f0db' 
  AND token = 'KxRS/urTHgeXzQkCapvZxGBSSOskqklVx+UZBpud+6w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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