SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a232a40af32567f8be1f3c882f7de158c948566c6a3fba9e007b8d5545266c3' 
  AND token = 'F/9MbjQhHBcupLKriRsqymOpSMaZVsTsBwcWtOPgsFU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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