SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3d8b7dc5e4ac37c9c1eb96b257fa8993f20bad401d29274d640f4fe916940f4' 
  AND token = '9D/Ot77dnkMUy1dXzVe1tp9pzv/FQQXK+J1naN951Rg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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