SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '511d98b4807a0d16bb3a94e9711bc29acadd74ee270a46d7c0bc0276e32600df' 
  AND token = 'xDcNH6J/2b7HaaBFE+IEIRzsyXz0HJR6nEL0FigXDdI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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