SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '08a3ac5d714ed8c4d57040f3051e8a3bf509cb17083b81f3091281ffa10de708' 
  AND token = '9f3OTd6nHRGZssK1Ul3bEBtPMs0R/vh0cN7CK0kYtDs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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