SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1e40dee2fdca8422f8ce57c1696e6b3b30a0817ee670615ee84a6c29b01948ec' 
  AND token = '6O9P8sKI3iLtwfH63DgzYEFwqaVjDIgttd3qsYbdT1o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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