SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f88f8bfc5ee9804d5b9f8362d2ce17302341619094cc231ef4215da0919b8a97' 
  AND token = '23X4ZXnHnxSKnEUZdmoZNOu6RwH2SwIvw+rQtt5kU6E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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