SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b8a65d1a977839447b936a63bd6d3d461e3cd4d93967d2e4a867b3eb772def0' 
  AND token = 'RQSCfxPhvKSlwCUVM7qwpWGWA6eF64xzTHckEYi/ve4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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