SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '67862b5cf001a8d8f351f73e38e157a05791b9f9b52c273afda4fd9a930e52d9' 
  AND token = 'Yp1fvGrziS2/XFM3gPugWhiwZdYZpFyuIBnsDsPfuJY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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