SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3d75ea1345c37a5f213c376f3d9ec7b9da958b9c56e5c02220794014ddcb41b' 
  AND token = 'Z3MyUK5Z8PRoMT47whaXf0yDE6mci12Ysj8vu3PxekU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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