SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '40f48e7df35e2ac1535f591711b85e2e385382d9b7c931395ed237bafafa4a7e' 
  AND token = 'SlBEu9GfMlTrVGUB/qxL6v6nW8CsnXPdcFelzhI/aW4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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