SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '67e5b8f18391743a3bf445f40e9271af6563e608cbf62ea1a4f98a820cb70dda' 
  AND token = 'mB7IcKvVibgwBe7V1HS17m6dBccac510wrBZxqQvKSY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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