SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f77a054354ef70af927f1f75bb86e465393b98badee44f56edf992ec2f62f04' 
  AND token = 'uIhgGDpXgxC8XsIzEHlggQYKpyr3qs4ZFiwwjtPvsLw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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