SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c2567f580d415b3e1218d91822a56c9264814745cfed39f2effadf4761f9708f' 
  AND token = 'l0ImJTZqQD11JyVRQDACwEN2m5dIueI2nhzsKSUrvOo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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