SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7685e8cb6546c8f5719f07b0d1d0e1bc54e3c296ade342965ba3241534d1a468' 
  AND token = 'RbhesQolouzVBwYygoRq3RVw6goYrmW9UGxNesDXFhI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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