SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '70fe6008791ea5452474c71f5888add135476b4bfe5b600ef71a7b4f33870831' 
  AND token = 'XM9NYcQAZQ7noMDFt5efjkcGwPNxrrBYznBCsJFEZZA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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