SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'acce8d4bb121bf0793994f8ecc30093b8dc4e24d9a92568432ffabb044c6f52d' 
  AND token = '3fOYcZmFk9fRU3rXu3zWI8vJtKAzz76G6o0aegscyzU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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