SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c0021a7872af5d637641fc35c046980b713abb582ed67ba9c91c5b022359d53c' 
  AND token = 'XMYonw08nyiEgEUQMZKjstH/fI+FDqEcDWyIW/+mKvU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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