SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31494fff60bcd38358162e09af9f885f9ed57d989c476e9d341973a26727f968' 
  AND token = 'OFKo17yOYHmluKTT6Ordl6iPZV+XwLoSnG+rMGr4idI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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