SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'fa3338073a8eda9feec2600561ce61a608bd8bbbdfb56514e955c1b5b2d43764' 
  AND token = 'VLXZAQzZhxe4l9VYGBq2a3cQfjmOk+qg3RURCpmzTvk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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