SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f5c32a0418246ea5244b82f989910be40fe6491e357fadde84b39be1f3e14879' 
  AND token = 'ShN5fj2+tQlXwwUCZmaUQguNKKi0zKeKhFhkSV21eSk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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