SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '999bff5ba854102addb3bffe5e1c8da4f325f5fc0053b0685b71adfdbef60424' 
  AND token = 'DNapYZB01eZynF9EKcvGj+DG0uZKWp23shAGkmR2SB8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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