SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '25ac9304039c82134d96f72443038ce9128066dad77ff1ffaa6185eecac79bba' 
  AND token = '7P5tge5SZYIkbSnpPG1bq8Id8CTUmwoSxZgIgb0H2sI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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