SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '67d57c21a96963457f12f524c758a78ae36946ca8fc6ee97fab9ffce2e876e8a' 
  AND token = '1bT8JsKF/qL+MlKq4SRhUw3kwwF8WIW73PBum0M68pY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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