SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '543e213e10c4280ab353326e31925e123382147c20679d9dbe3105e3e34d57af' 
  AND token = 'XgJTQzaKKazsu6SOKQpA9FplFpIan1cCj6eLPkE+Q8A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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