SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '678ccb9a0071ae643353f4cf64d15f859f38ae15793b14b18e89f356074b56d2' 
  AND token = 'wqIaBXznTboRx1VMcHqMQpAYzmJYgaAgbwq2AvxOMew=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00048

JSON explain

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