SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df8e0ce336a0a6bca559836a02e007b908099f785ed032689a75ed9921127639' 
  AND token = 'y6eQPTNIixQkzpdib1EuMUyRGERcAgNX22sDzTvNDE0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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