SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '939ae26030f45766034cc7e614b5e5b3699363bdb8e44b3576e8f3f3126a4f33' 
  AND token = 'v7RnEJB+ZSz+Dr3wVvVDNkdjvHfWRpd5q6inkgfgmyg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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