SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f766c24d277a5bb317df8b0e08b48a43b09b60314773727e426417693101472' 
  AND token = 'wj4mXFWgdop8gkHMrZegMRJaWQSI66lX1qt5cCx/bl4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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