SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91bf34d6864b71dc406fe6f9c466df802566e787385e9bf7af3c1172430d04de' 
  AND token = 'G34VN4bODmeDKlZjAx+aXF/yPFbcLhJpHPRc9DWkZ5g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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