SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '6fef30827ecbfc0d1b9aa581de6bda0186cbf248c87ff266c1edfd48551e1141' 
  AND token = 'e6tbf/t7v3kMShnI4sOSLKQGUWCuy47IUtXPuha3a48=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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