Sandbox

SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21d6dc3cded5b70cc4058be332a53bbfc70d6f3da4cf5d0d2b46efa7841f1a36' 
  AND token = 'PlJauXjzY3MiQLlJhvyIKYJEOxz9FTK4YKil9lKFpLc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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