SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f38a56748920c34dd2017d282151b04c8c712b28dde1ce4c63d9e3abecd8965' 
  AND token = '+WKwhtXNjRT45h3V4K5qwOTJBZwGHDvTrXe2RjHAthc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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