SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd3e2e6ed8445ee1aa4cf406585a321d364ac8f6b237b741e772675960fa66699' 
  AND token = '7w1ghM+Hi+F1lxAWbSVWk88b5lYncj5GvqATPthNNKI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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