SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a860e4030bed1c07daf09925383217213d7f86c08ea2e828410c3c36fb1eb844' 
  AND token = 'k59LlU+ZnVbGMf1BZZvEuvBY7viEbd+254+rtAtiamM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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