SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'afd44a2f3b08a3dd9eb03bf5044aefb8c91cbbfa6e8b321f496d9fe57471c59b' 
  AND token = '1cl4zAjAXDwK6OoAqz7Idz0FyLWu5Xvh/SY7RxwvV1Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

JSON explain

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