SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35f456a0ad26f9a68e774f09b2d070aee78986f2e91c6e6ab346b5fbc6668a53' 
  AND token = 'k63uobWJbAHDwM6M2Ayq5KpNNSeB1HUDDQehaGKjnsw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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