SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b339000b091bc0e05ff289d0ec36274c16baa337c7928ef5d621af2cda24ebd9' 
  AND token = 'lbhOBQFndFodQnTMnrpel5UECbSTreMO9h7LetE1xiQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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