SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3120646db641c9ce6bc70f8a34de53aa7a65243f7a42640710303a7257b8854f' 
  AND token = 'EXp2nfs7sjGRk0VLJUXzt+tqCMCoT4llHZunvFZzCSA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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