SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '6b89f33f03724e4c120450155ee9ea63912f0b72764a6691841bd11e949afe0c' 
  AND token = 'yZjk7sRHm6IyGJaoqumwH7KTdv4FWhxHcq5giyzgZmg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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