SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5a89944af395a856f166510bc119a4e7455987cb314d7b892aa4a9c942565636' 
  AND token = 'qkYbudKq1BGkswiOKRiXrPJ8fYiZ5okwN1ugYLxlYsU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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