SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b6856625414b4432816580739b68c4516380809168f41a307f2c64fba58293f' 
  AND token = 'RPsqAsS1Lc/YgeiJEr7WazBqHuS/JZ7cNOJCQ4ccFng=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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