SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '251d6a55b6d5963c8e256ff9448a5dc38b5580457fee49f6a4f9511ae1755ded' 
  AND token = 'LC8gCOEHEwxzd6WJFFNGDO9c++/Gzr5MrXnNU1ohoLI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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