SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fbe00cf6d2f797cc257fae67719688b90c812d7db758d55217c218851d7c51a0' 
  AND token = 'YjYZE4ovuZvraxMy4HUVxFZUdKhSBTcPpiUu/ADY3Z4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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