SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b931c10420f9684b2bd1ec82ce11ef65734a1170ec23ec855631a63cfddc8d27' 
  AND token = 'JsewYV3KEzcTm6lJ+yDgizKNr7XgNYrQO5SlIehnu9Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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