SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b3bbaa6ed0676dc4822a12515242952f257dd39612a3794f19691322040ce5c' 
  AND token = 'ixdKFlhrL9VdQRcXs00byLRRfYp1tZkddlGKSFYHNWI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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