SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'efae81f738714411518fb92f01279d2bdddf67f793e1dded1809d5b0fd5339a6' 
  AND token = '4GUvmCwUt7dUF5AIvEy+ljMb9fLQ9otIlmQCQZ8qoSw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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