SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '100231c8f6bb06cb24edd395fb877cbc9bc72db5949a3afca1fdcd5cf85155a4' 
  AND token = 'nCDDtrFkFnXBn7KKmZJEEKNxcm1aNfVYYeAUIXm68VY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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