SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '185290281026db7b7688186069ee1c2ab95bd562c18fc9109529c516e9bc2668' 
  AND token = 'VUhcRNdPDx5jameysi+WEORwAnlE8N91pp/Mr2UbTEI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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