SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '320555987387946d72b5a7eb27c211013d928c39ba428bf2e6733fb77c727734' 
  AND token = 'rHx1jBisrqo3txA+FdmaVXxN1rhZLuDrbWHShXhUrfY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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