SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b5b50296162fa289be531e6e09a51b07b1542cb694184fb49f67d12ec5875e2' 
  AND token = 'Fkue8Y4CMofhDPx5PmECXoVh4vJf+GjhTuTyDtgyGDw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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