SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2844c931ca53b775a46ddf0ba9e9c0589e582204b1fc4533b6b54f4629534cc3' 
  AND token = 'K9g+CAnoLnT9F3D7zphnQp+4fJHlKB/TmXKfbXy3qZA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00056

JSON explain

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