SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1967e9652b03613433f0bc6913977a75eb6e568a75a3e54d2da63a8689b2300f' 
  AND token = 'qUCBQgz9mEq+kJ2M5MhdzzHVIAdyel/V2IHCzu8MK8g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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