SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dfa644b823092ed7f6bd46d9f497842339c01b86bbe748cc1487c1ccb496a0fe' 
  AND token = 'KuljDiLN1NRleGOv5CGcbFqTgn5bwcIOnCpYfuOOxjo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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