SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '187f35fb4ab08185c9c4c022c2007fc2f272a10137eb007af198a429f0f8022c' 
  AND token = 'ByixaCRki/VSIRXu7lk5oKMSBEM6xOkTVoPIEB2aRjQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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