SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ceb430bc332b5e70fd3381191168567c5d42a4daf98a331d6f3af961535007f2' 
  AND token = 'zyA2UDC3UdncC/VZfodZRF+xz7VNxNeIDkoeeqVS7ic=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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