SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '13aa2ab5a32268176e7421e81b95d4aa559a31359a2850d02865210f78cc8f1a' 
  AND token = 'NRSwUvLRchuCTz+GmijZDyy01PQJl/b1YW6qZ9rUzC8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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