SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6c6a61902a557bfe91c76022576c99981cb4a5c8dbd71e84332c0cc95f61069' 
  AND token = 'mKgB9gAqhryGI+PYNTsLKEPSDZTN2RF6QPHCyXo0PsA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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