SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '501dbb05f93c237e8f57d1c421631393daa1b3b81efd439a3bbddc7543b79a0c' 
  AND token = 'QPXs5k2ijWQ1x+kKv8VYyoCW3FICICKgYZypbLJaX9E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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