SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a0ad64fe6e3e1cd069ebdc30e069c9fa4a18fabc12a0c6861efd9e38af4f9c41' 
  AND token = 'gdqmSDWa6kwYDD+yuXeRPvjLJUJ5ArQl76FgIC/BiAA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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