SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec218cc7fdac16e748d32a45c990a60f82e15ef6fb912f18d79b82d5bcb22fb3' 
  AND token = '/NzfhUx5kBeDpF0GKRgh7PgmOhBfWnanOh5Z22PIix0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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