SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '835b8a9eabc9d0c38137128eccdf6ce611cecb63e776ee982cd84db9f41fca02' 
  AND token = 'h8KzAkGDc6Tu+NwKSVckcxbhgwpTfR1PurZdINMpwI4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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