SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d86dd43541ad76fa1a3843b59354bd998ab2406df0d58c7774268ec91682411' 
  AND token = 'oUdsDpLGieoE96O1PuCh4N7lZSSO0hKS3t13OKhXBv4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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