SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '768ccb5652788557ccf0558a39d7360f9d53e9a12fe6bd22528905d44d621a38' 
  AND token = 'z9kEK/CfRSxc7FdVg3rmqgM/4uWb5cPS+qK50T4FmL8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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