SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd77dc94c9e2bd743a6d295c3c69259718fa9ca881f6e5158773ace05320defde' 
  AND token = 'VgxDPz3myxvBG9+DDVgUR0LkDD7xBHomtj/TVZypvLY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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