SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4854361b76a0953886bb1a66769fe38152580edd11e4d9fffff95726d19cc37' 
  AND token = 'WRraJOQt0djI3hj1fXAMoAORnlRduTxzHR4u6G2xRUE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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