SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6bc8541c855d57949e5fb145b24b16452c6a9c58abe66526664aa831bce82548' 
  AND token = 'dl5zFGb5qJfkjntluLqaXooEM2upHbRhFrdAToRDMgk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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