SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '82b19cd258b81643d1bfd4fa44f532e5bd6e7579b48d516b30c0227d67875e28' 
  AND token = 'sma/pUeqQLmuTyBHCrsgyNZ9meLQtp50JPHb/Jj/u0c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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