SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fcd3a6c41229cb7bcaa9bad0392e4673d9d517bb4baa3f7f5eaa5c6dcfbfba5d' 
  AND token = 'scB/HSU8TNRDUJNbufhzWrDavMBe5/MMIiVs1sEprWk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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