SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de6c582fc9f1ad86c750d6cac622725c2f00dea212c113b047dcfb7ff4454966' 
  AND token = 'WMcaFfEBM+AkDf8Tjv8Ulc+Vaywv1H0PjXsHRmNh/8Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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