SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '27fa5a56fbc8f6d0892831de15d006f2011ce9f3f93f0bacf95c6ad1fa239e04' 
  AND token = 'p9h5ngwKwYqb1/unDBFjpB0CUlqtZ1mRV/7VWtYY41Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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