SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9346e08d1918fe0f400bf2aad1646ea210fc0aa39a3bed5adb3dc05170a31b3' 
  AND token = '1hAiJ6tlMLJH1OaPVF++y/nnHfd6WMwZMhiq2tuOJng=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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