SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c9fa6385719544363bb5cdf7c0b4f4e879ff13bf9f5947dddbb2edf670beda1b' 
  AND token = 'W3kb1sEwPDjRIOxD5qqkqgU/WkGyXi5Fo5RyAIyPdkU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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