SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b6f4870d915ebea4fbebd60a5a78a4efca31e6507fa64fc1a2b69923942be8e' 
  AND token = 'm39HxxjOUvgw7772W0UDCl/oEtj7rAVNXjglRalqBq0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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