SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '708d44e753a227b040ee6a5f30efa501fc9863e3046b33a53ab8399aa515b3c7' 
  AND token = 'bFJ+p31cgmvGZT69iIYODipf6D0eAeOkxgPo+DddbaY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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