SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad0b1775d725919afa47db314d4f876c1c5097bc5c8e902598e8929f42e1af25' 
  AND token = 'a6GJYQyLY//wcvnQMJCcthSyB+Z+VvW6gPlQX5W2jSw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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