SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cbc421d42f7430e5f90e49330a092510d9ace391021e71525301940cf42f27b6' 
  AND token = 'ofBLpX7sqC7KTKKAaWctu2hRbScZLNjruCC3mWejsFM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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