SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35b9208eb403d3f72964ab26079ecda65028d558ce172efc86037f183a438f0c' 
  AND token = '/ZmSsSrqSAOr0syItfQR6+yO9/hiplTRr+t0uTxuwZw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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