SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7db0b29792d6c317f0788f0176cf67f831d1dd8e0043e70fcc46eb7876e62076' 
  AND token = 'TopQZe40CRIz6IUvIS8D7iMjw/IypIZt0RdMmnKW24A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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