SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3bb910ffa7e2508705153638067265b375406bbf0df545d3ef8473bc3e725157' 
  AND token = 'z9QuX1OLdtvfNnpbn3qQAGl6K+TiQ/W9cnWCbcM9Gyk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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