SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51c8c0ce724dfc2da9f95377398236e3a1673d66f9b730866bac907605c557bd' 
  AND token = 'IkgHlq0QONkNbj44Z6T5fh/YO90YwUZVlGGVBnuzHjA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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