SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '4c669b76aa7e7e8826f7f446694754f7482e3246f29a9b1e358688f03d07179b' 
  AND token = 'osA84agOoS2wzAgbosLKIUmBEQa7E3KFcvaXnYAFA7s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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