SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fcba95c0212dc4b9e27cac6256f48deab39b792f48d9f02bc5726c5bdf1b4802' 
  AND token = '/ZhOBsZiF/NkmvGrnb2bgC6PgCxB4rZtJzcwH5aaFjw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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