SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31cfeb0444e5e9ff146a18cb24d476d58a64234e2e280f0963e12c4eaa2a74fe' 
  AND token = 'a0tt3OSzDUP10p18Gfg1DtYrTYHzokMEWsQIkEy7Pn0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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