SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '791274dd29a2562ce35569af22cfe1885ebf60b07afb61656d8ca04d35dba778' 
  AND token = '3v0ztMpd9ZlUvgWWRN/mTjGetNRQ2eyyKvEAlmhGdBY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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