SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '540e121af2295f1db8e1803d04c8b925eb256379043f766f2ad72b8fdf061068' 
  AND token = '3/+3DZDuIB9LOIM5LGmapBcrle/jsiWFVY/Hl/PSdN0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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