SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '473926506d3bf3c8af0fa918d42459c72ba28f99019d18edbb16c1fed3923ce3' 
  AND token = '8HnveVGsWhEvQy6LmadSKbNqyPEELhBL0M7eGI51FbM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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