SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '323e29e1ed84228e5d7ea679116bd9e76b98ba3441a9c3e4b208448cd062c5d8' 
  AND token = 'WvKWUT2dEic4XJ75OsNJobUXsQg+pkZIoVf64Q9QNxc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}