SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cf42d1d1f55b4c94744ac337156767d5bebe917311e80fd5e9eaedceeb6e8fd5' 
  AND token = 'L//iJ6xuF1C7elFL5NMuddJqxjm9w6VxHbifTX1VnUk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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