SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16c15e9e2e72c34d418789b2673bc831b0022f28b13110e96383ace8eef9f762' 
  AND token = '9HUcCpNVdxyzfjIJgFelO2D/ZEZGFlf9DR0ktd9IW2A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00058

JSON explain

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