SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73dc97f7c075228ae197644476edbd735fb037c6254f873c4849bc821b57944e' 
  AND token = 'IuUALwrgSnxwH2bcmjxmw6qMZ+ehuRI2481LD5qe+yI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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