SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fed9b523f491dd3fbaf6e48f6c551289967a9f750fbb5958d77a32db3784c4a4' 
  AND token = 'r3BtbaXljP/JOUwRT+6/SdEWuJzRIwRb8PBLqTcepVI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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