SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0e42bbfcffc94f4a990017909ddcd83db795cf957c9db9fbc17a10e8cb3419a5' 
  AND token = '8DSw8uNf05t5etjLSv47zIXsj60pxEid2fbkqEE5NSU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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