SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '49431a36e609fddc23b960ae871bf2146a72f559cf251197d9c3a115149387b4' 
  AND token = 'VWZPKBEta5Pcb1utinbEmOBtMiyhBEqRuDg/KsLuJM0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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