SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef21b9b2056e6d8935def89797237ee0606f36db9ae87ab898980a72b43a6320' 
  AND token = 'h4MSIlZGCgYGWwFWqODT0Ge+cf3KDzMFXtQV02BnSJc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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