SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a41fb594b81e5e737f14c8950776637a543c2cb4efb4dce07491d34718a8d03f' 
  AND token = 'l6JqVZ/8xuRkl2HyR7YTG5Pi2DP/FUF12PHGN1GhztA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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