SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff895a5f51b3d716648ddd6a3c4fc8142f3309feca7292e922651f5362d27449' 
  AND token = 'KURjgiVZicqV8wuviSCIBSN8aF3TM+EKEQFXQbcPpaA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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