SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4f7daefc734fd17a7431541a62057be012fa7d5e75c245b7940f67bdbfd6b452' 
  AND token = '89CyDesT+gUA0RVxrYLhBrOFhbhHzPuK7XgoShBJ4sY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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