SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ae75521ea64d9c5ec9e7c370c3ad41170b04d01742f4480d26312a076df36d5c' 
  AND token = 'XMRStUcghJYPdSVlNjU31azqtCH9AxeHZBXvq6RXP0E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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