SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '84bf66c04636edafc5e092edf18eed9496228dc3c62f93f93f1d1434d296e756' 
  AND token = 'f/vTb3XTFdH9QTcuuefbeFe2dLmkkr5vt8vBSvoy510=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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