SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5efa698f34ee6d87ff78b8566cde52b6310c0c5efc376c97242202d23297e71' 
  AND token = 'aRgE7wnxm4jcbK6yksfVEgCfEMvE513GTeIXFZVZBpo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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