SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e81cd981a66d6560b507a7824bc38bb679fceee9e2a0a5f82cb1f5bbc0e5243d' 
  AND token = '83P+5QTIyQSmfW0gowCWjrAWfTtPHAU8QLbTg8e6Nmw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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