SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '633b155295b5d6bc615faebbc9d8314db6e34be13b0f523f4260b8a8f17a9726' 
  AND token = 'lUdgikYVdgxXz/VSozgUs6tsnmSZPQh5vwnbxVmrTI8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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