SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81621150d0423388fa0c6e1f5dec8ae2c99ba0994536bbaf2401127a3846e59e' 
  AND token = 'KpaKVHwCDmqN5HD5Uj+V6XIwhpidZoKxcInQLvtzCB0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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