SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'b7f51b175d475198493b0ca8cb193f56bcc39de26761d1f1ee50001f8ee29979' 
  AND token = 'cDQR5qeUm+29E1nfj9aF3nfPxq5ipU/bnI9iHZU9FEE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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