SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38dc7248788d8a4b0455954334602eb8553d8dab5085c9f1871af290c4314e10' 
  AND token = 'vnCsC962iA+rOo+ypO+yhxGmqVhsfODXmcYjPSZO1TU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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