SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'b8521ecfe0023f8f32a4ad310c0056fc74f7a5313a09b8e86ca0c4e551704f36' 
  AND token = 'iaUfGsWJRwOWSM9JBFrIXi3La/Xxed9LAGZHKjwj3QE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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