SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35be63f67f016d164bddeaae4d0c5fc4295e06c560a3268a96629c80341d233f' 
  AND token = 'qGCqkH96tcjMXAtNPbSZbSdv6omzPeJMQbKS//vOTo4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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