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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fed9e73c20d7fad4e245ff0a7b8211d96d723a8a74ef818712d5cd98a9780a6f' 
  AND token = '6Np6YHTtIE8lkGZGAiMTz9bxG/Re4XP3sXQ6M2Ap6uY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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