SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68d0412586428b621dc206f2f26ecd63c726c1b5f6102405b6381d3fb623c627' 
  AND token = 'ik8CF1Q7lUiMtGoIAmzegmuChd1b6KV9XWd3w4VAB3Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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