SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb92ac80c462a3c63169409a08d0f515a58d5f05d1d44ad6b678fbab8ebe7a03' 
  AND token = 'ONTodylUCI4hSRCB8iJt9UswRuxf7B7I9Ou/zMp4bVY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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