SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb6ce4a26f705a9308f999e4b286e9190b137425236f5a71ffce9a5333d175a8' 
  AND token = 'R1YgfYcHr5MKPrwZ0ANQllvbENGYPq2I4UX8NIbDcUg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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