SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ffd74c390124c09ac938a668b34ed2d9c8137d21a6ae00b19aff286af46c0e27' 
  AND token = 'RqDRtFRzjm6i35r+vavs3bZYx3Sh2KylWqIlgi0LXxQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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