SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '24b160bef9f972c581891a90e40fd646e641287723145fd4c92ff357d114c63c' 
  AND token = 'syo8IjNWSXEHbs9FffNalCwoLIzZLLTrkNvyM8Q0CA8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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