SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c43ba92476a236f5d6231e71d86996507fbed1f72ee87e2c0f2b52a3b70cb43' 
  AND token = 'ZOG0sNYJuhSbFV4ClW19f7wxLr1kvqWk8FXpVal4zwI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}