SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f5e15a948a6867878cbfa5fd7447c4fc039cc6f037cd77c8af3ebee3a852b793' 
  AND token = 'Qe2CTYit1PTxmCgzLQMAd9mH3qYLMcusJghcdQhGC9E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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