SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c6d0d1aa008a3b915a43ea3378370f469090967fc8d8cfc935678ee2f8ff655' 
  AND token = '7lr84eJ35nn0dRqzLMBG01jVBz66X0R9o1rU9KoaJcI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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