SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c011335a4cd81b900970055d23e00276cf6b8254f5b41a14e8117234e4013f5f' 
  AND token = 'VQlIA1MuqCuLK5c8t2gzdiJnC+9m04GduylRZPnYDXk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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