SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ccdbccc141688f1f51182d21c26249320162477857e2139065f03f6c8d32cc1' 
  AND token = 'Q1S1IbQmFuzEt4ms18DkLeFfSHSzHxWlYdrth8IIiok=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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