SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b1346a747d0933f67d3bb6f55b2c8c5821d55616c8cfbdb6dc638e87bb6a5517' 
  AND token = 'kw3cKyC1EDmCwjI+giGS/dytaC4pDmmM4GnbxdC3Bs0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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