SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ca2509cba875a543986e87fe97c8ed1e6c84a9bf9d71b6841fd725be7afd1ab9' 
  AND token = 'mHSfcadJ6pgphkfWZBpzNm5I8c4j4blHWnCPZ2IHRi0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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