SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'db555792049a6ff720b3ee60a7ea66f2588bd311fc927b6f17e68b977166b0eb' 
  AND token = 'vf+MxFeDdWzZ8G5mGwN9MggLVSjRDvPvUp3un0saaYI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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