SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '66bd27d66dc00521f599264b7bdf5853974f2d12052275e1a9f607a9d3bce05a' 
  AND token = 'aN9N6RLS5u7JVPxpMIueeuVGA+F+Z6+tCDQkXNDBQdw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}