SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4fa134e71fae621df173d12035bc65a2ca14fea7158d38409d668636b352efe3' 
  AND token = 'RCKCeUDFarHoLbBTpvkXPi0np7IKnf9xwij/UApWYYc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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