SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fcf612ea4f66d1ca784079872f2bb65824a0ad9733541e4e2f636477ded829aa' 
  AND token = '/1czFw71A15Qlcmalij0qFBYNT+QxnC+KhBGCLjd3HQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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