SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '549409f1468a3044b271545ad9026fef03c9d028112c704a8e3cfa797e83fd9c' 
  AND token = 'yd4FcUJWUDmJggndKU1YXrafvYZiY+7ybdqEhY4qpus=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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