SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8467ad88b30d73e837bd5d2b29dc26ec0dc22ea19b540c28617e45fffc29e458' 
  AND token = '3htFriLtCynHziIjl8O9nl7ykhzlgE2AsQtEjkzDXD4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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