SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'b6391798dd68ff6a530fda716cd73a7f00a14b1c4dd1c9e47d6a12518eb00569' 
  AND token = 'zCpu1wfBuhCGvEp/p0sVlBzZqWhqKfoY8bYuTzyC320=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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