SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '786efd817cfaa853755f51b55273140139bb03b9feed020bf048c648d97141d2' 
  AND token = 'cQaYhjUHy60laTlFLcauxV1nlcpFMWHbfk2CDYZgTqw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}