SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '157be8ddc7c77fcb413deaf39fb23add5feb9b726e9c96e43d28a76d54a46326' 
  AND token = 'hagUcnYMYmnTXhyYGaWwpPNBgO78ZCIZmjdpohlUuRA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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