SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8445a4b3ed77718789224efb6dd6f3b7f1d638befd88d068c4371756de2d6503' 
  AND token = 'I4Rz/vJF5gTTzUZ9FLiG/xeIjnl4HkXj+QxKSkKT9jA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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