SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '34fea19425817a88b151c87c2309e5510e8aac02e71f4c3451daabbf4ac39f24' 
  AND token = 'rBjrlZybQENPMb4XdBTUNW1iHYjkcZibc4wmtYa1zFQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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