SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '33bc52f8208c52d3fafe36047a6e0e1e2a2600ac9e395804fd4755b8c399b593' 
  AND token = 'l/m28XFqQ/+jhofH07rKQoWXEPF/qnuerubL7YwzuVs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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