SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f8c4acb1febd15cd6ed0d5259226022f552d387b03681c30f3ffe19cacc0ae6c' 
  AND token = '8z0jhUd2Clam7uXR3qG78tATIDyh7iuypiqS8C918nU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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