SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe8ebfb732769e048fc2722324ff5f93444bae908aa1d2526d6f90bcc0493ecd' 
  AND token = 'txBXEd/JQWgxGSqhYyNbiSH6QcXTlFZ8UeFxGrhCR9Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}