SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81b875dc8741e6647941000e29bd9c198a85205795da669110c85c72fd9a986f' 
  AND token = 'IAg7osdpZMgEkcSfS8T/I49MEkZ/GsjbLk6ILm4J+Ho=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00048

JSON explain

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