SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0d3d878273e957c221203b575ccf2ec5c0e721b9959f144f60d97b9d913ef851' 
  AND token = '2u8JZywT60ZBJ5D6Q8shRAsWLx6vGaqY2UCjZ3V44iU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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