SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb0fe570462f46984bed80ae8551b82340153242fc13528503550820d6c574b0' 
  AND token = 'CMmJTD17r6ZtMXtW5+XxrcfcXTGTbc+tovD8oee7egk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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