SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '005c6547512b7f882d3546167003a8f1e808a681af4dc6d69311f09847c3708f' 
  AND token = 'czjZEBzTbNUvMgSo80/Vy0co9QYPDfsCbpeqtQKGmjQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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