SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b52ed2d52ff358ea96bbf5e4f944487f2352535c51edde6746e8e36df9caa626' 
  AND token = '3KHmSHLVJY65TYTOqwFVKjbDVvSnSf4N1zeglxq+fNE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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