SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '342f97513f943cd4adf78cfb19c3b352da39b188b625ce2100f0d83565222a84' 
  AND token = 'wjP5aerSUZR21JohDrzeZMBrokw84NV6K0TcWn3v/MA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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