SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5a7195207d10abcd338a031ba68d499fc669f7eac04fe12b351cf4d0f269e67' 
  AND token = '9849LD72hNICoX4fLgJKDSXA+hwKRBNjhX5RkTl/nHg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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